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PRINCIPLES OF SANITARY SCIENCE 
AND THE PUBLIC HEALTH 












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Principles of Sanitary Science 
and the Public Health 

WITH SPECIAL REFERENCE TO 

THE CAUSATION AND PREVENTION OF 
INFECTIOUS DISEASES 



BY 

WILLIAM T. SEDGWICK, Ph.D. 

PROFESSOR OF BIOLOGY AND LECTURER ON SANITARY SCIENCE AND 

THE PUBLIC HEALTH IN THE MASSACHUSETTS INSTITUTE OF 

TECHNOLOGY, . DSTON; SOMETIME BIOLOGIST TO THE 

STATE BOARD OF HEALTH OF MASSACHUSETTS 



"With all deductions, the triumphs of sanitary reform as 
well as of medical science are perhaps the brightest page in 
the history of our century." — W. E. H. Lecky 



THE MACMILLAN COMPANY 

LONDON : MACMILLAN AND CO., Ltd. 
1902 

All rights reserved 



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CLASS A 


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Copyright, 1902, 
By THE MACMILLAN COMPANY. 



Set up and electrotyped April, 1902. 



Nortoooti $«88 

3. S. Cushing & Co. — Berwick & Smith 

Norwood Mass. U.S.A. 



TO 

Efje State Boat* of P^altij 
of jfttagadjusetts 

FAITHFUL THOUGH UNPAID GUARDIANS OF THE PEOPLE 

IN WHOSE HONORABLE SERVICE 

THE AUTHOR BEGAN AN ACQUAINTANCE WITH PUBLIC HYGIENE 

AND STRENGTHENED A LOVE FOR SANITARY SCIENCE 

WHICH HAVE INCITED HIM TO WRITE THIS BOOK 

AND ESPECIALLY 
TO 

Sfentg ^during TOalcott, PUB,, Chairman 

AND 

J^iram jFramte Pills, &.%., lEngmeet iHemfrer 

"Even to the State's best health." 

— Timon of Athens. 



. 



PREFACE 

With the single exception of the change effected by 
the acceptance of the theory of organic evolution, there 
has probably been no modification of human opinion 
within the nineteenth century more wonderful, or more 
profoundly affecting the general conduct of human life, 
than that in our attitude toward the nature, the causation 
and the prevention of disease. The modern conception 
of the living body, whether plant or animal, as essentially 
a physical mechanism, is largely the result of discoveries 
in the domain of physics and chemistry begun, indeed, 
but not perfected, before the recent century. The mod- 
ern conception of disease as due to imperfection, misbe- 
havior or disturbance of a physical mechanism depended 
for its development on an acquaintance with the physiology 
of the body and its microscopic structure which did not 
exist before the introduction, in the third decade, of the 
achromatic objective. The microscopical renaissance which 
began with this pregnant invention speedily led to dis- 
coveries of the first importance in the normal structure 
of organized bodies; disclosed in abnormal tissues the 
material ravages, and, in some cases, the parasitic origin 
of disease ; brought into full view a flora and a fauna hith- 
erto unseen or only half seen ; and, by the end of the fifth 
decade, was throwing a new and increasingly powerful 
light on the long-vexed question of the relation of fer- 
ments and fermentation to decomposition, putrefaction 
and disease. At the end of the sixth decade a new theory 
of infectious disease — the "germ" theory — had arisen, 



vin PREFACE 

and in the hands of Pasteur, Lister and many others was 
already bearing fruit. 

The last quarter of the century has witnessed the firm 
establishment and fruitful development of these several 
conceptions. The principal theories to which they have 
given birth have been thoroughly tested, and stand to-day 
for the most part as accepted scientific principles ; while 
their applications to the practical conduct of life have 
everywhere been followed by results of extraordinary in- 
terest and importance. Public hygiene and state medicine 
have become subjects compelling the attention of states- 
men and affecting the welfare of nations. Sanitary law 
has been endowed with unusual privileges and powers, 
and sanitary regulations controlling the commerce of the 
civilized world are debated in international congresses. 
Sanitary science and preventive medicine, terms practically 
unknown before this century, have become almost house- 
hold words. Sanitary arts of great range and importance 
have grown up ; vast sums are annually spent for private, 
and especially for public, sanitation ; and human life has 
been made safer, longer and probably happier. 

Standing on the threshold of the twentieth century, and 
surrounded by the innumerable municipal, medical, domes- 
tic, public and private sanitary safeguards which have 
already sprung from these discoveries so that, in spite 
of facilities for the spread of disease by the development 
of easy international transportation, such as the world has 
never before known, pestilences and plagues are no longer 
greatly dreaded, it is hard to realize that our not very 
remote ancestors regarded disease as an insoluble mystery, 
an inscrutable visitation of divine Providence, or as the 
penalty and consequence of sin. Under such beliefs there 
could be no sanitary science. But if disease be disturb- 
ance of a physical mechanism, and due to the fact that 
the mechanism is made of poor materials, or of good mate- 
rials badly put together, or that it is badly operated, or 



PREFACE ix 

that it is interfered with by unfavorable environmental 
conditions, it becomes easy to comprehend at least ap- 
proximately the causes of diseases, and in many cases to 
remove or forestall them. It is precisely this which the 
science and art of hygiene seek to do, namely, to compre- 
hend the nature of the human body and its diseases, in 
order as far as possible to prevent the latter. Hygiene is 
the science and art of the conservation and improvement 
of normal living, the prevention not merely of premature 
death but of abnormal life ; and sanitary science, or hygi- 
ology, is simply the body of scientific doctrine, or the 
principles, underlying the sanitary arts. 

The time has not yet come for a scientific treatise on 
the whole subject of hygiene. The application of many of 
the results of experimental science to the welfare of man, 
extensive and valuable though they are, must still wait 
until their relations to everyday life become clearer. 
Climatology, clothing, warming and ventilation, foods and 
feeding are subjects undoubtedly of the very first impor- 
tance, but not as yet reducible in their relation to human 
life to simple scientific terms. It is otherwise, however, 
with an important class of diseases proceeding from the 
controllable environment and known as " communicable " 
or "infectious." In principle, at least, these are now well 
understood and capable of being scientifically dealt with. 
Their causes are known, as are also the sources in which 
they originate, and the vehicles by which they are trans- 
ported. Their characteristic operations and effects are 
rapidly becoming familiar everyday facts. Their control, 
therefore, in theory at least, becomes easy and in a broad 
sense a problem of engineering, which subject has been 
defined as the scientific control and use of the forces and 
materials of nature for the benefit of man. So much, at 
least, of medical or sanitary engineering rests upon a sound 
scientific basis, and for this the term "sanitary science," 
as distinguished from " hygiene," may conveniently be 



X PREFACE 

employed. If, hereafter, our knowledge of the consti- 
tutional diseases, and the ordinary conduct of individual 
life, comes to rest upon foundations equally sure, simple 
and scientific, either term — hygiene or sanitary science — 
may be dropped, for the two will be strictly synonymous. 
Until that time comes it will probably conduce to a just 
recognition of the real situation if we keep the term 
" hygiene " more as an end to be sought for than as some- 
thing possessed, and endeavor by the constant extension 
of the boundaries of knowledge and the application of the 
principles of science, to enlarge the field of sanitary sci- 
ence until its boundaries become coterminous with those 
of hygiene. The mutual relations of hygiene, sanitary 
science, public hygiene and personal hygiene are dwelt 
upon at some length at the end of the first chapter, and to 
that place those are referred who care to pursue this sub- 
ject further. 

The present volume is the direct outgrowth of a course 
of lectures on Sanitary Science and the Public Health 
given for several years by the author to certain senior 
students — chiefly engineers, biologists, chemists and archi- 
tects — of the Massachusetts Institute of Technology, and 
it has been prepared primarily for their use. It is be- 
lieved, however, that a larger circle of students and some 
physicians, publicists and general readers may be glad to 
have access to the same material. If any apology is 
required for the occasional use of examples drawn from 
the author's personal experience, chiefly in Massachusetts, 
it may be said that these have been referred to, not because 
the author regards them as of paramount importance, but 
because he has preferred to deal as far as possible at first 
hand with matters within his own knowledge rather than 
to depend upon the digests or even the original reports of 
others. 

It must not be forgotten that this volume deals with the 
principles, rather than the arts, of sanitation, nor that it is 



PREFACE 



XI 



based upon lectures given to beginners. It is intended to 
be no more than an elementary treatise on the subject ; 
and while it is believed that it contains some new mate- 
rial, and some old material treated from new points of 
view, no special claim is made for originality either in 
substance or in method of presentation. The author has 
chiefly sought to bring together and to present in a simple 
and logical form those fundamental scientific principles on 
which the great practical arts of modern sanitation securely 
rest. The subject is so vast and touches human welfare 
at so many points that it has seemed wise to omit many 
things altogether, and to make in many cases only brief 
and summary statements where more extended treatment 
would have been easy and perhaps desirable. It is hoped, 
however, that clearness and accuracy have nowhere been 
sacrificed to mere condensation. 

The author has prepared the present work in the 
earnest hope that it may find a useful place in sanitary 
education, both professional and popular, for he holds 
with Lord Derby that " sanitary instruction is even more 
important than sanitary legislation." 

The Biological Laboratories, 

Massachusetts Institute of Technology, 

December, 1901. 




FlG. I. {After Leuckart-Chun s Wall- Diagram.) —ANOPHELES AND THE MALARIA 
Germ, i, 2. The malaria germ (Plasmodium) introduced by a mosquito bite 
into human blood. 3-5. After penetrating a red-blood cell ; its growth at the 
expense of the latter. 6. Its vegetative multiplication. 7, 8. Crescentic forms 
(for further development the germs must at this point be transferred from the 
man to mosquito). 9. Female germ-cell ; 9 a, 9 b, Male germ-cell. 10. Conju- 
gation of 9 with one of the vibratile arms of go. 11. Malaria germ resulting 
from such conjugation in stomach of mosquito. 12-16. Multiplication (encyst- 
ment and sporulation) of the malaria germ in the body of the mosquito, with 
production of many forms like 1 (cycle completed). 17. Female malarial mos- 
quito (Anopheles claviger) ; head of male below. 19-20. Mosquito larva and 
pupa. 21. Stomach of mosquito, showing tumors produced by 16. 22. Cross- 
section of salivary gland of mosquito, showing malarial microbes which have 
wandered into it (from the tumors in 21) and now ready to be transferred with 
saliva into persons bitten. 



. 



CONTENTS 
PART I 

HEALTH AND DISEASE 

CHAPTER I 

On Health, Old Age and Disease. A Classification of Dis- 
eases ACCORDING TO THEIR PLACE OF ORIGIN. DEFINITIONS 

The Human Mechanism — Old Age — Death and its Causes — 
Disease, not Old Age, the Principal Nominal Agent of Death — An- 
other View of the Causes of Death — Intrinsic, Constitutional or 
Structural Defects of the Vital Machinery — Intrinsic or Constitu- 
tional Diseases — Extrinsic or Environmental Interferences with the 
Vital Machinery — Extrinsic or Environmental Diseases — The Pre- 
vention of Constitutional Disease the Special Function of Personal 
Hygiene — Environmental Diseases more readily controlled — Their 
Prevention the Special Function of Public Hygiene — The Pre- 
vention of Premature Death the Principal Function of Hygiene 
and Sanitation — Hygiene and Sanitary Science — Definitions. 



CHAPTER II 

On ^Etiology or the Causes of Disease; Ancient and Modern 
Theories. The Zymotic (Ferment) or Germ Theory of 

Infectious Disease 21 

The Primitive or Daemonic Theory — Theory of the Four Humors 
— Roman, Arabian and Mediaeval Theories — Theory of Paracel- 
sus — Physical and Chemical Theories — Theory of Sydenham — 
theories of the Eighteenth Century — Influence of Haller and 
Morgagni — Theory of Hahnemann— ^Theories of the Nineteenth 
Century*— The Germ Theory of Fermentation — The Zymotic or 
Germ Theory of Infectious Disease — Louis Pasteur and Infectious 
Diseases of Silkworms — Joseph Lister and Infectious Diseases of 
Wounds — Sanitary (Aseptic) Surgery the First Fruit of the Germ 
Theory. 






xiv CONTENTS 



CHAPTER III 



PAGE 



On the Rise and Influence of Bacteriology. Transformation 
of the Zymotic into the Zymotoxic Theory of Infectious 
Disease 46 

The Achromatic Objective — Animalcula, Vibrionia, Bacteria — 
The Beginnings of Bacteriology — Its Foundations securely laid by 
Louis Pasteur — Robert Koch proves that Micro-organisms are the 
Cause and not merely the Consequence of Splenic Fever — Photo- 
graphs and Spores of Bacteria — A New Method for Bacterial Cul- 
tivation — Establishment of Bacteriology as a Science by Koch in 
1881 — Quick Discovery by its Aid of the Germs of Tuberculosis, 
Typhoid Fever, Asiatic Cholera, Diphtheria and Tetanus — How 
precisely do Germs produce Disease ? — Sepsins, Ptomaines and 
Toxins — Transformation of the Zymotic Theory of Infectious Dis- 
ease into the Zymotoxic Theory of To-day — Objections to the 
Germ Theory. 

CHAPTER IV 

Sanitary Aspects of the Struggle for Existence. Parasitism. 
Health and Disease in Terms of General Biology. Vital 
Resistance, Susceptibility and Immunity .... 62 

Sanitary Aspects of the Struggle for Existence — The Parable of 
the Sower — Parasitism and Infectious Disease — Parasites and 
their Hosts — The Germ Theory a Theory of Parasitism — Materies 
tnorbi — The Lifeless Environment and Disease — Organisms and 
their Environments — Health and Disease in Terms of General 
Biology — Three Principal Sanitary Conditions or States of Relation 
— Their Practical Importance — Sanitary Paradoxes — Vital Resist- 
ance — Susceptibility — Immunity — Inoculation for Small-pox — 
Jenner and Vaccination — Pasteur and Attenuation — Metschnikoff 
and Phagocytosis — Behring and Antitoxic Serums — Serum as 
Cure and Serum as Prevention — Summary. 



CONTENTS xv 



PART II 

INFECTION AND CONTAGION: THEIR DISSEMINA- 
TION AND CONTROL. FUNDAMENTAL PROB- 
LEMS OF PUBLIC SANITATION 

CHAPTER V 

PAGE 

On Infection and Contagion : the Paths and Portals by which 
they enter the body; the resistance which it offers; the 
Vehicles by which they are conveyed; and the Places of 
their Origin. Animals and their Excreta as Sources and 
Prime Movers of Infection 89 

The Meaning of " Infection " — The Skin and Epithelia as Struc- 
tural Defences of the Living Body against the Invasions of Disease 

— " The Solution of Continuity " — Infection by Way of the Skin 

— Wounds and the Diseases of Wounds — Tetanus or "Lockjaw" 

— Insects as Vehicles — ^Mosquitoes and Malaria, Yellow Fever^ 
etc. — Flies and Typhoid Fever — Infection by Way of the Ali- 
mentary, Pulmonary and Genito-urinary Tracts — Toxins again 
— The Physiological Defences of the Living Body — "Vital Re- 
sistance " — " Susceptibility " and " Immunity " — The Precise 
Meaning of " Contagion " — Personal Contact (Contagion) vs. In- 
fection and their Relative Efficiency in the Distribution of Disease 

— Man and Other Animals the Principal Primary Sources of 
Infection — Man and Other Animals and especially their Excreta 
its Principal Primary Vehicles — Earth, Air, Water and Animals 
(Insects, etc.) the Principal Secondary Vehicles of Infectious Dis- 
ease. 

CHAPTER VI 

On Dirt and Disease. The Living Earth. Dirt, Dust and Air 
as Vehicles of Infection. Filth and Filth Diseases and the 
Philosophy of Cleanness 108 

^Precise Meaning of the Terms " Dirt," " Earth," " Soil," " Dust£_ 
etc. — Their Popular Significance as derived from Experience — 
Clean Earth vs. Dirty and Infectious Earth — Modern Ideas of a 
Living Earth — Earth as a Vehicle of Disease — Tetanus — Dust as 
a Vehicle — Its Dangers — The Atmosphere as a Vehicle of Disease; 
Ancient and Modern Theories — Pestilential Vapors; Atmospheric 
Influences; Miasmata — Microbes of the Air — Filth and Filth 
Diseases — The Pythogenic Theory — Modern Views of Filth and 
Disease — The Philosophy of Cleanness — Personal vs. Public 



xvi CONTENTS 

PAGE 

Cleanness — Public Drinking Cups, Towels, Razors, etc., and their 
Dangers — The Disposal of Dirt, Dust, Garbage and Refuse — 
Cleanliness — Its Aseptic and Antiseptic Value. 

CHAPTER VII 

On Sewage as a Vehicle of Infectious Disease : its Proper Dis- 
posal and Purification; the Natural Purification of Sew- 
age by Fermentation and the Living Earth . . . .123 

The Genesis and Composition of Sewage — Its Dangerous Ele- 
ments and Properties — The Importance of its Sanitary Disposal — 
Primitive Methods of Disposal — Modern Methods — Disposal and 
Purification by Dilution — Disposal in Rivers — "The Self- Purifica- 
tion" of Streams — Disposal in Lakes — Disposal in Harbors, Estu- 
aries and the Sea — Principles involved in these Cases — Disposal 
and Purification on Land — The Living Earth — Intermittent Fil- 
tration — Experiments in England — In Massachusetts — The Law- 
rence Experiment Station — Theory of Intermittent Filtration — 
* A Bio-chemical Process — Objections to Intermittent Filtration — 
Disposal of Sewage by Irrigation — Sewage Farms — Objections 
to Sewage Disposal by Irrigation and Sewage Farming — Disposal 
and Partial Purification of Sewage by Chemical Precipitation — By 
Electricity — By Fermentation or Putrefaction — Fate of the Infec- 
tious Materials in the Disposal and Purification of Sewage — Sew- 
age Fields and Sewage Filters as Bacterial Tombs. 

CHAPTER VIII 

On Water as a Vehicle of Infectious Disease. The Pollution 
of Public Water Supplies. Notable Epidemics due to 

Infected Drinking Water 164 

Drinking Water as a Vehicle of Disease — Diarrhoeal Diseases 
and Drinking Water — Typhoid Fever and Asiatic Cholera — An 
Epidemic of Asiatic Cholera traced to a Polluted and Infected Well : 
the Case of the Broad Street (London) Pump — An Epidemic of 
Asiatic Cholera in London in 1866 traced to an Infected Public 
Surface-water Supply — An Epidemic of Typhoid Fever in Lausen 
(Switzerland) traced to an Infected Public Ground-water Supply — 
An Epidemic of Typhoid Fever in Caterham (England) traced to 
a Polluted Ground-water Supply — An Epidemic of Typhoid Fever 
in Plymouth (Pennsylvania) traced to a Polluted Surface-water 
Supply — Typhoid Fever in Lowell, Lawrence and Other Cities on 
the Merrimac River — Pollution vs. Infection — The Case of New- 
buryport (Mass.) — An Epidemic of Asiatic Cholera in Hamburg 



CONTENTS xvii 

PAGE 

(Germany) traced to an Infected Surface-water Supply — An Epi- 
demic of Typhoid Fever in New Haven (Conn.) traced to an 
Infected Surface-water Supply — Diseases Other than Typhoid 
Fever and Asiatic Cholera traced to Polluted Drinking Waters — 
Dysentery and Diarrhoea — Concluding Remarks on Drinking 
Water as a Vehicle of Disease. 

CHAPTER IX 

On the Establishment and Conservation of Purity in Public 

Water Supplies 221 

Public Supplies as Public Dangers — The Atmosphere as the Source 
of Water Supply — The Pollution of Rain Water and of Snow by 
Dust — Influence of the Earth upon the Purity of Rain Water — 
" The Living Earth " again — Ground-waters and their Pollution 
and Purification — The Conservation of Purity in Ground Waters; 
Microscopical Organisms and Noxious Tastes or Odors — Surface 
Waters and their Pollution — "The Self-purification of Streams" 
once more — Quiet Water rather than Running Water purifies 
itself — Natural Processes of Water Purification — Purification by 
Storage — By Slow Sand Filtration — Artificial Processes of Water 
Purification — Rapid Mechanical Filters — Conservation of Purity 
in Surface Waters — Recapitulation — Protection by Statute of the 
Purity of Inland Waters in Massachusetts — Sanitary Protection of 
Public Water Supplies — Advanced Legislation — Sanitary Inspec- 
tion and Protection of Watersheds — Expert Supervision an Abso- 
lute Requirement of Sanitary Science. 

CHAPTER X 

On Ice as a Vehicle of Infectious Disease. The Pollution of 
Ice. Ice Supply and the Public Health . . . .251 

The Use of Ice in Drinks — Does Polluted Water purify itself in 
Freezing ? — Epidemics charged to Infected Ice — Investigations 
of the Purity of Ice by Various Observers — Ice as a Vehicle of 
Infectious Disease — The Pollution of Ice — General Inferences 
and Conclusions. 

CHAPTER XI 

On Milk as a Vehicle of Infectious Disease. The Pollution 
and Infection of Milk. Epidemics traced to Infected 
Milk. Milk Supply and the Public Health . . .263 

Milk as Food for Microbes and Mankind — The Modern Dis- 
trust of Uncooked Milk — Its Origin in Epidemics traced to Milk 
— The Fermentations of Milk — Normal vs. Fermented Milk — 



xviil CONTENTS 

PAGE 

Infantile Diarrhoea and Cholera Infantum — The Pollution of Ordi- 
nary Milk — Various Systems of Public Milk Supply in Villages, 
Cities, etc. — Milk Supply in Warm Countries — Epidemics of Ty- 
phoid Fever in Massachusetts traced to Infected Milk Supplies — 
Epidemics of Typhoid Fever traced to Skimmed Milk and Cream- 
eries — The Question of Tuberculosis in Milk — Scarlet Fever and 
Diphtheria — The Protection of Milk Supplies from Pollution — 
Their Protection from Infection — Safeguards against Polluted and 
Infected Milk — Sterilization — Pasteurization — Condensation — 
Modification — Model Dairies — The Outlook for Improved Milk 
Supplies. 



CHAPTER XII 

On Certain Uncooked Foods (Meats, Oysters, Fruits, Vegeta- 
bles, Ice Creams, etc.) as Vehicles of Infectious Disease. 

The Sanitary Significance of Cookery 293 

An Infectious Disease {Trichinosis) produced by Microscopic 
Worms in Raw Pork — Trichina spiralis — The Question of Infec- 
tion by Tuberculous Meat — Raw Oysters as a Vehicle of Disease 
— An Epidemic of Typhoid Fever traced to Infected Oysters — 
English and French Opinion in Regard to Dangers from Raw Shell- 
fish — The Contamination of Oyster Beds by Sewers — Fruits, Vege- 
tables, Ice Creams, etc., as Vehicles of Disease — The Sanitary 
Significance of Cookery. 



CHAPTER XIII 

On the Prevention and Inhibition of Infection, Decomposition 

and Decay. Asepsis and Antisepsis 311 

Asepsis, or the Prevention of Infection by Exclusion — Quaran- 
tine — Isolation — Immunity, or the Prevention of Infection by 
Insusceptibility — Inoculation — Vaccination — Progress in Vacci- 
nation due to the Labors of Pasteur — A Public Demonstration of 
Protective Inoculation or " Vaccination " for Anthrax — Antisepsis, 
or the Inhibition of Infection by Antiseptics — Antiseptics and the 
Theory of their Action — The Control of Infection, Decomposi- 
tion and Decay — Intestinal Antisepsis — Sanitary Aspects of Re- 
frigeration and Cold Storage — Of Desiccation (Drying, Evapora- 
tion) — Of Smoking — Of Preserving — Of Canning — Of Pickling 
— Of Pasteurizing — Of Condensing. 



CONTENTS 



CHAPTER XIV 



xitf 



On the Destruction or Removal of Infection — Disinfection 

and Disinfectants 334 

Definitions — Disinfection by Chemical Agencies — Fire, Poisons, 
etc. — By Physical Agencies — Heat, Cold, Dryness, Light, 
Electricity, etc. — By Mechanical Means — Filtration, Sedimenta- 
tion, etc. — By Biological Agencies — Starvation, Old Age, " Un- 
favorable Environments," etc. — The Problem of Disposal of the 
Dead — Interment vs. Cremation — Special Disinfectants — Germi- 
cidal-efficiency Tests — Present State of the Art — Intestinal Disin- 
fection. 



PART III 

APPENDIX 

On Some Popular Beliefs as to Certain Special and Peculiar 

Causes of Disease 347 

The Belief in Dangers from Sewer Gas — The Belief in Dangers 
from Well Water — The Belief in Dangers from Broken Drains — 
The Belief in Dangers from Bad Smells — The Belief that Con- 
sumption is Inherited and therefore a Constitutional Disease — The 
Probable Truth about Endemic Disease — The Belief in Dangers 
from Atmospheric and Telluric Disturbances — The Belief in Dan- 
gers from Damp Cellars — The Belief in Dangers from Human 
Breath — The Probable Truth about Disease from Putrefaction and 
Decay — From Spoiled Meats — From Ice Cream Poisoning — 
From Canned Foods. 



PART I 

HEALTH AND DISEASE 



. 



SANITARY SCIENCE AND THE 
PUBLIC HEALTH 



CHAPTER I 

ON HEALTH, OLD AGE AND DISEASE. A CLASSIFICATION 
OF DISEASES ACCORDING TO THEIR PLACE OF ORIGIN. 
DEFINITIONS 

"The fundamental conception of the living body as a physical 
mechanism ... is the distinctive feature of modern as contrasted 
with ancient physiology." — Huxley. 

"To die of age, is a rare, singular and extraordinarie death." 
— Montaigne. 

§ I. — The Human Mechanism 

We must endeavor to obtain at the outset clear ideas of 
what is meant by the words " health " and " disease," which, 
to physiologists at least, are terms of precise and definite 
meaning indicating actual states or conditions of the living 
body. A moment's consideration will show that it is essen- 
tially no more difficult to comprehend the idea of a general 
state or condition of a living body than a general state or 
condition of a lifeless body, such as a stone or a piece of 
iron or a watch or a locomotive. 

Closely examined, the living body reveals itself as a 
machine or mechanism composed of parts (called organs) 
precisely as a watch does. Very much in the same sense 
that a watch is a time-piece a living body is a life-piece. 
If a watch appears to be in good order and running well, 

3 



4 HEALTH, OLD AGE AND DISEASE 

we say that it is a good and normal time-piece. So also if 
the human body appears to be in good order and working 
well, we call it a normal or healthy body ; but if it be out 
of order and not working well, we say that it is in a state 
of " disease," either temporary or permanent. In a word, 
health is the normal, and disease the abnormal, condition 
of the living mechanism. Nor is this a mere analogy or 
abstraction. To the biologist it calls up a picture — the 
picture of health or the picture of disease. For precisely 
as the experienced watchmaker carries in his mind's eye 
and can at any moment summon up a mental image of 
intricate, correlated and interdependent parts — springs, 
wheels, bearings — lying concealed within, but which, taken 
together and in a certain definite and orderly relation one 
to another, make up the works of a delicately adjusted 
chronometer in actual operation, and constitute a valuable 
time-keeper; so the physiologist, familiar with bones, 
muscles and nerves, with good red blood and beating 
heart, all cooperating to a common end, — the healthy, 
normal life of the organism, — can summon up at will the 
picture of normal, vigorous, almost superfluous vitality in 
some vascular life-keeper. And in one sense, hardly more 
wonderful to him is the pulsing, vibrant, living mechanism 
than to the jeweller the accurate chronometer of delicate 
adjustment. To the savage the watch would be incompre- 
hensible and inexplicable. And so to others than physi- 
ologists the living body seems something altogether strange 
and wholly apart. 

The student of sanitary science must take up the physi- 
ologist's point of view. He must look upon the living 
body as a mechanism ; a mechanism of curious origin and 
history and of marvellous complexity; the most wonder- 
ful of all machines ; one before which the wisest of men 
stands very much as does the savage before the chro- 
nometer, ignorant of its origin, ignorant of its ultimate 
construction, ignorant of its fate; but yet unlike the 



THE HUMAN MECHANISM 5 

savage because without superstition and without fear; 
knowing that the body is nevertheless a mechanism, sub- 
ject to natural laws, and with all its parts cooperating to 
one end, — the life-keeping function of the whole. The 
living body is like a machine, also, in that it receives all 
its energy from without and is merely a transformer of 
energy; in that it is profoundly sensitive (as is a watch) 
to its environment — to heat, to cold, to mechanical inju- 
ries. This living machine may be well built or ill; of 
good timber or poor; it may be sound and flawless or 
defective in construction. These are accidents of birth 
or ancestry; effects of good feeding or bad, of normal 
living or abnormal. 

§ 2. — The Making of the Body. Youth and Maturity 

Unlike the watch, the living mechanism is not made, but 
grows. With the fusion of two unlike cells — ovum and 
spermatozoon — the life of the individual begins. Hence- 
forward its increase in size, its acquirement of organs and 
tissues, its powers and properties, are due, not as in the 
making of a watch to the assembling and cooperation of 
parts already perfected, but to processes of its own, to cell 
growth, cell multiplication, cell differentiation — balanced, 
adjusted, directed and controlled chiefly from within. 
The first portion of this development takes place within 
the body of the parent, and is called intra-uterine or 
embryonic life ; the second is a helpless state outside the 
body, but under parental care, the period of infancy ; a 
third, somewhat less dependent but ill-defined, is the 
period of childhood and adolescence. These three periods 
— the periods of youth — ripen into adult life or maturity, 
and this passes on into old age. Only very rarely does 
the mechanism last longer than a century. Usually, long 
before this it has stopped in death, which may have marked 
the end of life at birth, or even long before it, in infancy, 



6 HEALTH, OLD AGE AND DISEASE 

in childhood, in maturity or in age. The period of growth 
and the period of decline — infancy and old age — appear 
to be the periods when death is least successfully resisted. 
As has been finely said : " In this last respect the two ex- 
tremes of life resemble one another. The freshly lighted 
taper and that which is burnt down to the socket are both 
easily extinguished by the slightest puff of wind." 1 

§ 3 .__ Old Age 

Finally the living mechanism may wear out — it must 
wear out. No machine, however perfect, can run or be 
run forever. However smooth its bearings, however per- 
fect its adjustments, dust and friction, and wear and tear, 
do their work, and in time the machine becomes old. So, 
also, is it with the human mechanism. No matter how 
well cared for, or how cleverly managed, old age finally 
creeps over it ; the rust of rheumatism gathers in its joints; 
its bearings grow eccentric ; its movements irregular and 
halting; until by and by something breaks, and death 
stops the whole machinery. Death is the final stoppage 
of the living mechanism. But while theoretically this 
comes only when all parts are worn out, and as the 
simple, natural cessation of function from sheer and gen- 
eral debility of each and every organ, it does not in fact 
come very often in this way. The machine breaks down ; 
it does not wear out. Some organ or part gives out 
comparatively early, and by failure to do its part destroys 
the whole. 

Facts like these may or may not have inspired the author 
of the " One-Hoss Shay," who, in his famous poem has 
described the building of the body ; its defects of consti- 
tution and construction ; the ordinary causes of its death ; 
and, finally, the theoretic possibility of so making a living 
body that it shall die at last only because it is worn out, 

1 P. H. Pye-Smith, "Lumleian Lectures," London, 189a. 



A PHYSIOLOGICAL ALLEGORY 7 

namely, from old age. In the person of the deacon the 
Autocrat, himself a physiologist, has, consciously or uncon- 
sciously, stated the case as follows : — 

" Now in building of chaises, I tell you what, 
There is always so?newhere a weakest spot, — 
In hub, tire, felloe, in spring or thill, 
In panel, or cross-bar, or floor, or sill, 
In screw, bolt, thoroughbrace, — lurking still, 
Find it somewhere you must and will, — 
Above or below, or within or without, — 
And that's the reason, beyond a doubt, 
A chaise breaks down, but doesn't wear out." 

His remedy for this unfortunate state of things was, — 

" only jest 
T' make that place uz strong uz the rest." 

Accordingly the deacon proceeded to build his master- 
piece in such a way that — 

" The wheels were just as strong as the thills, 
And the floor was just as strong as the sills, 
And the panels just as strong as the floor, 
And the whippletree neither less nor more, 
And the back cross-bar as strong as the fore, 
And spring, and axle and hub encore" — 

with the result that after a whole century of life though 
there were indeed 

..." traces of age in the one-hoss shay, 
A general flavor of mild decay," 
there was 

11 nothing local as one may say ! " 

And when the end came from sheer old age, — 

..." it went to pieces all at once — 
All at once, and nothing first — 
Just as bubbles do when they burst." 

Such is old age: the low-burning flame, which flickers 
and finally goes out ; the ripened fruit, which drops heavily 
to earth; the old mechanism, which after long years of 



8 HEALTH, OLD AGE AND DISEASE 

service finally refuses to work, simply because it is worn 
out. All this is the natural and ordinary course of life. 
With this sanitary science has but little to do except to 
exercise a wholesome supervision and watchfulness and to 
provide the most favorable environment possible. With 
ordinary breakdowns from defects in the machine itself, 
in its construction, or its operation, sanitary science has also 
little if anything to do. Good stock comes by inheritance 
not by manufacture, as truly in men as in timber. Men 
do not gather grapes from thorns or figs from thistles. 
Neither do strong constitutions, as a rule, spring from 
weak ancestors or good lungs from tuberculous parentage. 

§ 4. — Death and its Causes 

Life is the period of activity of the vital mechanism. 
Death marks the final stoppage of that machinery. Life 
is a perpetual struggle of the organism with its environ- 
ment. Death marks its final and unconditional surrender. 
In the higher forms of life death is the natural and inevi- 
table end of life. Old age marks the approach of death 
and is not less natural and inevitable. Doubtless the 
principal cause of death should be old age, the natural 
maturity of the organism, the gradual and irreparable 
wearing out of the vital machinery. Yet if we turn to 
any work on vital statistics, such as a Registration Report, 
we find far more prominence given to other factors of 
mortality. In the enumeration of the causes of death in 
the Registration Report of Massachusetts, for example, 
there are laid down five general classes of causes, namely, 
as follows : — 



I. 


Zymotic Diseases . 


(Fevers, etc.) 


II. 


Constitutional Diseases . 


(Gout, Cancer, Scrofula, Dropsy, etc.) 


III. 


Local Diseases 


(Apoplexy, Heart Disease, etc.) 


IV. 


Developmental Diseases 


(Teething, Old Age, etc.) 


V. 


Violence 


(Drowning, Murder, Accidents, etc.) 



THE PRINCIPAL AGENTS OF DEATH g 

If we look for old age, we find it under Class IV counted as 
a disease along with teething, — an equally normal process 
of the living organism. The great variety in the causes 
of death may be still more clearly seen by counting the 
subdivisions of the foregoing classes which are in number 
as follows in the Registration Report referred to : — 

1 32 Causes of Death 

II io " " " 

III 48 * « * 

IV ^ . . 10 " " " 

V 14 " " " 

It will be seen that Classes I-IV include seven-eighths 
of all the recognized causes of death. In other words, 
various forms of disease constitute seven-eighths of all the 
recognized causes of death, and it only requires a some- 
what closer examination of mortality tables to show that 
ofd age is assigned as the cause of death in a very small 
percentage of cases. 

§ 5. — Disease t not Old Age, the Principal Agent of Death 

% From the previous paragraph it is clear that disease is 
the cause of death most often assigned by physicians in 
filling out their official certificates; while old age, which 
may be considered the most natural cause, is compara- 
tively rare. But this is much more apparent than real, 
since it often happens that disease would have been power- 
less to cause death if the vital machinery had not already 
been weakened by age. To what extent death is really 
due to age it is, and always must be, impossible to say. 
The truth appears to be that many deaths occur under, 
and are attributed to, disease which would not have been 
able to cause death had the victim been either older or 
younger; while, on the other hand, death would not have 
occurred when it did if disease had been absent. 

There occurred in Massachusetts, in 1890, 45,108 deaths 



10 HEALTH, OLD AGE AND DISEASE 

from specified causes, and all but 1814, or four per cent, 
were assigned by the physicians reporting them to the 
effect of some disease. Disease, violence and old age, 
then, would appear to be the principal causes of death; 
disease causing about ninety-two per cent, violence four 
per cent, and old age four per cent, and if disease is thus 
in reality, as it is apparently, the principal agent of death, 
it is obviously to the prevention of disease that sanitary 
science must address itself. Hence has arisen its synonym 
"preventive medicine," i.e. such action as shall prevent the 
ravages of disease. 

§ 6. — Another Classification of the Causes of Death 

A simpler, and for our purpose more helpful, view of 
the causes of death is one which seeks to classify them 
roughly according to their apparent place of origin, simply 
regarding them as either — 

(a) Intrinsic causes, or arising within the body proper, or 

(b) Extrinsic causes, arising outside the body or acting 
upon it from without. 

From this standpoint diseases may be regarded as due 
either to defects in the constitution or construction of the 
vital mechanism, or else to external unfavorable influences 
acting upon it. From the point of view of origin or causa- 
tion, all diseases may be divided into two classes, viz. : — 

I. Constitutional, or 
II. Environmental 

This classification, while open to many objections, is of 
the highest value to the physiologist and the sanitarian, 
for it brings the former face to face with intrinsic, struc- 
tural, or organic defects in the mechanism, while the atten- 
tion of the latter is concentrated upon those abnormal 
external influences which act unfavorably upon the organ- 
ism, and which he must seek, and may be able, to remove. 



BIOLOGY AND SANITATION II 

A count of the principal causes of death laid down in the 
Registration Report of Massachusetts shows that on this 
basis, and approximately speaking, there are there given — 

(i) Extrinsic or environmental causes of death . ... 56 
(2) Intrinsic or constitutional " " " .... 58 

In other words, one-half of the principal assigned causes 
of death, from this point of view, may be said to proceed 
from within the organism and one-half from without ; one- 
half would therefore lie within the domain of the physiol- 
ogist and one-half within the field of the sanitarian. It 
will be found instructive to carry this line of thought 
considerably further, as in the next following sections, 
carefully keeping in mind the fact that many so-called 
intrinsic causes probably have in reality, though perhaps 
only remotely, an extrinsic source or origin. 

" Any arrangement of diseases is valuable so far as it 
helps the memory to retain useful facts ; any arrangement 
is useless or mischievous if it pretend to be a universal 
or ' natural ' or ' scientific ' system. Diseases are not 
natural objects ; they are physiological states, which we 
sometimes define by their cause, as plumbism [lead-poison- 
ing] and scabies [itch] ; sometimes by their histology, as 
sclerosis of the spinal cord and epithelial cancer of the 
lip ; sometimes by their constancy in transmission, as 
measles and typhus ; and sometimes by more or less con- 
stant concurrence of symptoms, as chorea and epilepsy." 1 

§ 7. — Intrinsic or Structural Defects of the Vital 
Machinery ; Constitutional Diseases 

The human body is a wonderful machine, an admirable 
piece of mechanism. Like other complicated machines, 
it has a definite structure and interdependent and recip- 
rocating parts. These are naturally adjusted to the per- 

1 Pye-Smith, " Diseases of the Skin," London, 1893. 



12 HEALTH, OLD AGE AND DISEASE 

formance of certain duties or functions, and a failure of 
one part may involve the failure of all other parts and 
thus of the entire vital apparatus. If, for example, the 
heart is defective and fails to do its duty, the circulation 
is affected unfavorably and the whole body suffers. It 
needs no further argument or illustration to show that a 
structural flaw or defect in the living machine may mean 
disaster and death, however favorable all external condi- 
tions may be. A condition of the blood, or a roughness 
upon the valves of the heart, which shall produce a clot, 
or a weakening of an arterial wall in the brain which shall 
finally produce cerebral hemorrhage or cause apoplexy, 
is an intrinsic or structural defect which may not be 
directly attributable to any unfavorable external condi- 
tion. It may be a flaw in the machine, an intrinsic and 
perhaps inherited defect of structure; and, if so, it is 
remediable only by fundamental changes in organization 
which sanitary science cannot hope to establish, unless 
after many generations and by steps which are at present 
quite beyond its reach. Diseases of this class are dis- 
eases of construction, i.e. " intrinsic " or " constitutional." 
They belong as yet in the field of the biologist, the physi- 
ologist and the hygienist rather than that of the sanitarian ; 
to personal hygiene, rather than public hygiene or sanitary 
science. 

§ 8. — Extrinsic or External Interferences with the Vital 
Machinery ; Environmental Diseases 

The human body is subject — sensitive, even — to exter- 
nal conditions : cold or heat, fire or water, may so act upon 
the human body as to produce death by freezing, burning, 
or drowning. Forces, such as gravity or electricity, may 
be causes of death by falling, crushing or execution. 
These and similar causes are clearly extrinsic or environ- 
mental, and come under the head of accident or violence 
— unless we except suicide as perhaps due to constitu- 



CONSTITUTIONAL VS. ENVIRONMENTAL DISEASE 13 

tional peculiarities. Some diseases have already been 
spoken of as constitutional or intrinsic, but many dis- 
eases do not come under this head. The common 
expression which describes an infectious disease as an 
"attack" is noteworthy as indicating the popular recog- 
nition of the fact that disease often has its source out- 
side of the body. It is now believed that many diseases 
originate exclusively from unfavorable environmental in- 
fluences, and since the celebrated discovery of 1839 of 
the vegetable nature of the cause of favus (honeycomb 
of the scalp), it has been found that not a few diseases 
are due to parasites, which invade the organism and inter- 
fere with its normal working. 

§ 9. — The Prevention of Constitutional Diseases the Special 
Function of Personal Hygiene 

If diseases due to defects or flaws in the vital machinery 
are to be avoided, this is obviously to be done only by 
improving and perfecting the apparatus, which is a com- 
paratively slow and difficult matter. To make a family 
of weak constitution strong, is to reconstitute its entire 
physical basis ; and if this can be done at all, it may be 
only after generations shall have come and gone. It must 
be done by careful living and good feeding, wise inter- 
marriage and severe natural selection. To ward off adven- 
titious disease is, in these cases, not enough. The whole 
structure must be made over. Sanitation alone cannot 
hope to effect these changes. They must come from 
scientific hygiene carefully applied throughout long 
generations. 

§ 10. — Extrinsic or Environmental Diseases mainly Pre- 
ventable and therefore within the Scope of Sanitation 

Diseases which arise from some invasion of the organism 
may possibly be warded off. As they virtually proceed 






14 HEALTH, OLD AGE AND DISEASE 

from the environment which, in theory at least, is under 
our control, they may be prevented. With such diseases 
the sanitary science of to-day is chiefly concerned. Sanita- 
tion has stamped out small-pox in many civilized com- 
munities. It is seeking to-day, with more or less success, 
to do away with typhoid fever. It boldly attacks epidemics 
of diphtheria and scarlet fever, and has recently sought to 
control tuberculosis and malaria. There can be no ques- 
tion that it has already won signal victories, and that its 
practitioners may reasonably hope for fresh laurels in the 
near future. 



§ ii. — The Prevention of Premature Death the Principal 
Function of Hygiene and Sanitary Science 

From what has been said above it would appear that dis- 
ease is the principal agent of death. But it must be kept in 
mind that disease (except in infants) is often facilitated in 
its work by age or enfeeblement, which gives it a foothold 
and incapacitates the organism for resisting its activity. 
Physiologists and physicians recognize differences of con- 
dition in which the body seems to possess great powers 
of resistance or endurance, or only small powers (p. 71). 
In this way it often happens that a structural or constitu- 
tional enfeeblement exposes the organism to the invasion 
of environmental disease ; as, for example, a low condition 
of vitality is generally believed to increase enormously the 
susceptibility to attacks of typhoid fever ; and as soldiers, 
enfeebled by long marches or bad feeding, appear to suffer 
unduly from certain camp diseases. 

A little reflection will show that death, as a rule, comes 
prematurely. Old age, the only theoretically normal and 
natural cause of death, is very rarely the one and only 
cause. Poor timber or poor materials or poor construction 
of the living machinery, alone or together making up a 
poor "constitution," or else violence, poison, parasites or 



THE FUNCTIONS OF HYGIENE 15 

other unfavorable elements in the environment, usually 
bring on disease and death long before the appointed 
threescore years and ten, or the rarer fourscore years. 
Many die before they are born ; more before one year of 
life is over ; others under five years, ten or twenty. A 
few live on for thirty, forty or fifty years ; but for the 
great majority death comes before old age, before "the 
lean and slipper'd pantaloon." All this means that death 
is oftenest premature ; and the principal function of sani- 
tation and of the applications of hygiene in general is the 
prevention of premature death. Hygiene in its widest 
sense goes further, and seeks to elevate or maintain at a 
high level the standard of normal living. 

§ 12. — Hygiene and Sanitary Science 

Sanitary science is the science of health. It is com- 
monly held to be, and commonly it is, much the same 
thing as hygiene. Sciences and arts, however, like living 
organisms, grow, differentiate and divide, and hygiene is 
no exception to the rule. The wonderful developments 
which have taken place within the last half century in our 
knowledge of the causes of disease, and especially those 
diseases proceeding from the environment, together with 
the corresponding advancement in our arts for their pre- 
vention or control, — the sanitary arts, — have brought about 
a differentiation of hygiene such that one portion of it now 
deals naturally and mainly with the environment of man, 
while another portion deals naturally and mainly with man 
himself. 

As the environment is usually shared in common by 
many persons, that branch of hygiene which deals mainly 
with the environment may conveniently be called " public " 
hygiene; while the remainder, dealing as it does chiefly 
with the individual, may properly be designated "personal " 
hygiene. Underlying both personal and public hygiene 



1 6 HEALTH, OLD AGE AND DISEASE 

there are certain fundamental principles of the causation 
and prevention of disease which are absolutely essential 
to all sound practice of the sanitary arts. These, steadily 
growing in number and importance as the years go by, 
constitute the firm foundation on which both the theory 
and the practice of personal and public hygiene rest. 
Moreover, because they are founded largely upon experi- 
ment, and are in harmony with established laws of nature, 
they may be said to constitute the beginnings, at least, of 
a sanitary " science." Furthermore, inasmuch as the en- 
vironment is not only more accessible for treatment than 
the individual, but also far more under our influence and 
control, it has naturally come to pass that sanitary science 
consists very largely of principles derived from, and ap- 
plicable to, problems relating to the environment rather 
than the individual. Hence it happens that it is at pres- 
ent most often and most naturally associated with public 
hygiene or the public health rather than with general 
hygiene or with personal hygiene, or the health of the 
individual. 

The whole subject of proper food and clothing, for 
example, pertains to general or personal hygiene; but 
sanitary science is more especially concerned with infected 
food and clothing. Whether the citizens of Boston or 
Paris dress warmly enough, or too warmly; whether cot- 
ton, linen or wool is, on the whole, the most suitable for 
the climate of New York or London at all seasons or at 
any season — these are questions of general or of per- 
sonal hygiene ; but the question of infection by means of 
clothing made in the den of the sweater; the question 
of the disinfection of Egyptian rags arriving in the harbor 
of London or Boston ; the conveyance of disease germs 
by the clothing of persons dead of small-pox or scarlet 
fever — these are the peculiar property of sanitary science 
and the public health. To sanitary science and the public 
health belong also questions of polluted water, polluted 



SANITARY SCIENCE OR HYGIOLOGY 17 

milk and polluted air; questions concerning the origin, 
dangers and disposal of sewage ; questions relating to 
dust and disease and to the natural history of epidemics. 
The practice of sanitary science is founded, as applied 
science must always be founded, upon a basis of estab- 
lished truth. Upon this sure basis we may construct a 
framework of philosophical explanation, or theory, by the 
aid of which we may hope to make or measure new dis- 
coveries. Though often unrecognized, some such working 
theory lies at the bottom of all sanitary endeavor. It has 
underlain the prayers and incantations of savages ; it under- 
lies all quarantine regulations ; it is at the foundation of all 
sanitary authority. 

The past fifty years have witnessed vast additions to 
our store of established truth, and vast changes in our 
stock of theory, underlying all the application of sanitary 
science. These additions we owe almost wholly to one 
simple mechanical discovery in the domain of physics — 
the discovery how to make an achromatic microscope 
objective. This discovery so facilitated and stimulated 
the use of the microscope that it has revolutionized ideas 
of the causation of disease; has established physiology 
upon a broad and firm foundation ; and has created new 
sciences of immense importance, such as general biology, 
pathology and bacteriology. 

§ 13. — Definitions 

As a recapitulation of the foregoing paragraphs the 
following definitions may be found useful for beginners, 
although like most definitions they are only approximately 
correct and must not be taken too literally. 

HYGIENE 

Hygiene {general hygiene) is the whole science and art 
of the conservation and promotion of health both in indi- 



1 8 HEALTH, OLD AGE AND DISEASE 

victuals and in communities. It has for its function the 
prevention of premature death and the promotion of nor- 
mal life, health and happiness both directly by conservation 
and reenforcement of organisms and groups of organisms, 
a?id indirectly by the elimination or amelioration of unfa- 
vorable environme?ital conditions both local and general. 

The field of hygiene is immense, for it includes not only 
all of sanitary science and the sanitary arts, but a large part 
of physiology and even of biology as well. It includes not 
only questions of water supply, milk supply and sewerage, 
but also much of climatology, foods and feeding, clothing, 
heating, lighting, ventilation, vaccination, scavenging, the 
personal care of the body, work and overwork, sleep, rest, 
fatigue, exercise, play, sports, noise, crowding and over- 
crowding, and other subjects too numerous to mention but 
comprised in part under the heads of public hygiene and 
personal hygiene, municipal sanitation, school sanitation, 
household sanitation, offensive trades, unwholesome or 
dangerous trades, quarantine, toxicology, etc. 

PUBLIC HYGIENE 

Public hygiene is the science and the art of the conserva- 
tion and promotion of the public health. It has for its 
function the prevention of premature death and the promo- 
tion of normal life, health and happiness in communities 
chiefly by the elimination or amelioration of unfavorable 
environmental conditions common to many persons or com- 
munities either at one time or at different times. 

It includes especially hygienic problems common to 
groups or communities, such as camps, villages, towns 
and cities, e.g. water supplies, drainage, milk supplies, ice 
supplies, the control of infectious diseases, heating, light- 
ing, ventilation, school sanitation, municipal sanitation, 
and the like. The establishment of municipal gymnasia 
in many cities shows that the necessity of muscular exer- 
cise under the conditions of urban life is becoming a ques- 



DEFINITIONS 19 

tion of public as it has long been of personal hygiene. 
There is undoubtedly a natural tendency for all questions 
of personal hygiene to become more and more problems of 
public hygiene. 

PERSONAL HYGIENE 

Persotial hygiene is the science and art of the conservation 
and promotion of personal health, and has for its function 
the prevention of premature death and the promotion of nor- 
mal individual life, health and Jiappiness chiefly by direct 
conservation and reenforcement of that physical mechanism 
which we call the human body. 

It includes especially problems relating to proper foods 
and feeding of the individual, his sleep and rest, his work 
and fatigue, his muscular exercise, stimulants and narcotics, 
the care of the eyes, the ears, the teeth, the bowels, the 
hair and other organs, clothing for special conditions, etc. 

SANITARY SCIENCE (HYGIOLOGY) 

Sanitary science (hygiology) is that body of hygienic or 
sanitary knowledge which having been sufficiently and criti- 
cally examined has been foiind so far as tested to be invari- 
ably true. Its phenomena are natural phenomena, its laws 
are natural laws, its principles are scientific principles. 

It includes those hygienic facts and theories which have 
been so thoroughly verified by repeated observation and 
experiment as to have become worthy to rank as scientific 
principles. A good example of such a body of fact and 
theory is that which underlies, and is correlated by, the 
germ theory of infectious disease, which is described in 
the next chapter. Like some other sciences, while largely 
inductive it is also in part deductive. 

THE SANITARY ARTS 

The sanitary arts are those methods and processes by 
which the applications of the principles of sanitary science or 
hygiene are effected. 



20 HEALTH, OLD AGE AND DISEASE 

They include the practical processes involved in all 
sanitary engineering and architecture, e.g. in water-supply, 
sewerage, ventilation and heating, municipal sanitation, 
school hygiene, etc. Among the most important are 
the construction and operation of reservoirs, filters, con- 
duits, sewers, sewage fields and hygienic schoolhouses, 
the cultivation and preparation of vaccine, the manufac- 
ture of antitoxines, the inspection of foods and drugs, the 
examination of drinking waters, the disposal of garbage 
and refuse, the construction and maintenance of streets, 
the abatement of nuisances, the control of dangerous or 
offensive trades, etc. 



. 



CHAPTER II 

ON .ETIOLOGY OR THE CAUSES OF DISEASE. ANCIENT AND 
MODERN THEORIES. THE ZYMOTIC (FERMENT) OR GERM 
THEORY OF INFECTIOUS DISEASE 

W How far the power of spirits and devils doth extend and whether 
they can cause this or any other disease, is a serious question and 
worthy to be considered. 11 — Burton's "Anatomy of Melancholy." 

" Diseases and death are the consequences and effects of sin ; this is 
the idea which we have of them from Scripture. 11 

— Cruden's " Concordance. 1 ' 

"Diseases have been generally considered as the inevitable inflic- 
tions of Providence. 11 — Malthus. 

" Diseases . . . will perhaps be never properly understood without 
an insight into the doctrine of fermentations." — Boyle. 

" Side by side with these . . . has run the germ theory of epidemic 
disease. The notion was expressed by Kircher, and favored by Lin- 
naeus, that epidemic diseases may be due to germs which . . . enter the 
body, and produce disturbance by the development within the body of 
parasitic life." — Tyndall. 

" Moreover, if inquiry into the origin and conditions of disease helps 
treatment, it is indispensable for the still better art of prevention. That 
depends entirely upon the extent of our knowledge of aetiology." 

— Pye-Smith. 

The sanitarian must have sound working theories of 
disease. If he is to maintain and promote the public 
health, he must be familiar with the causes of disease 
and the avenues along which they travel. In order to 
prevent disease he must know, if possible, precisely what 
disease is. To-day all civilized and scientific persons re- 
gard disease, as has been indicated in the preceding 
chapter, as a state or condition of disturbance or abnor- 



22 ETIOLOGY OR THE CAUSES OF DISEASE 

mality 1 which the body has unfortunately assumed or 
been placed in. Savage and uncivilized people, on the 
contrary, and the unscientific civilized, are apt to look upon 
disease as an entity, something to be pacified, cajoled or 
cast out. Very often this entity is personified, and illus- 
trates that subjective characteristic which is so marked a 
feature of primitive culture. 

§ i . — The Demonic Theory of Disease 2 

The earliest theories of disease with which we are ac- 
quainted are found among savage races, which naturally 
interpret fever, sickness, pain, madness and hysteria as 
due to the temporary or prolonged occupancy of the 
affected body by an evil spirit or demon. This is called 
the Demo?iic Theory. The same subjective, anthropomor- 
phic method of thought which sees in the sun, not a huge 
sphere of burning matter giving light and life to other 
worlds, but Apollo, a god, driving his chariot of fire daily 
across the sky ; or fills the woods with fauns and satyrs, 
and the streams with nymphs and naiads, naturally looks 
for the causes of disease in human or inhuman forms dis- 
torted and misshapen according to the fancy, but gifted 
with human cunning and more than human malignity. 3 

1 " Disease is a state of a living organism ... the disease itself is a per- 
turbation. . . . " — Allbutt, " Syst. Med.," I. xxiv. 

2 For the substance, and to a great extent the form, of this entire section 
the author is indebted to various writings of that eminent authority on 
primitive culture, Professor E. B. Tylor. 

3 " Among races of low culture, the conception of a ghost soul being made 
to account for the phenomena of life readily leads to a corresponding theory 
of morbid states of body and mind. As the man's proper soul causes the 
functions of normal life by its presence, while its more or less continued 
absence induces sleep, trance, and at last death, so the abnormal phenomena 
of disease have a sufficient explanation at hand, in the idea that some other 
soul or soul-like spirit is acting on or has entered the patient. Among the 
cases which most strongly suggest this, are : first, such derangements as hys- 
teria, epilepsy, and madness, where the raving and convulsions seem to 



PRIMITIVE THEORIES OF DISEASE 23 

The demonic theory regards disease as a supernatural 
being or entity, not primarily as a process or condition, 

by-standers like the acts of some other being in possession of the patient's 
body, and even the patient is apt to think so when he ' comes to himself; 
and second, internal diseases where severe pain or wasting away may be 
ascribed to some unseen being wounding or gnawing within. This applicabil- 
ity of demoniacal possession as a theory to explain disease in general is best 
proved by the fact that it is so often thus applied by savage races. Especially, 
reasoning out the matter in similar ways, rude tribes in different countries 
have repeatedly arrived at the conclusion that diseases are caused by the 
surviving souls or ghosts of the dead who appear to the living in dreams and 
visions, thus proving at once their existence after death and their continued 
concern with mankind. This notion being once set on foot it becomes easy 
to the savage mind to identify the particular spirit, as when the Tasmanian 
ascribes a gnawing disease to his having unwittingly pronounced the name of 
a dead man, who, thus summoned, has crept into his body and is consuming 
his liver ; or when the sick Zulu believes that some dead ancestor he sees in 
a dream has caused his ailment, wanting to be propitiated with a sacrifice of 
an ox ; or when the Samoan persuades himself that the ancestral souls, who 
on occasion reveal themselves by talking through the voices of living members 
of the family, are the same beings who will take up their abode in the heads 
or stomachs of living men and cause their illness and death. ... In many, 
perhaps in most, cases, however, the disease demon is not specially described 
as a human ghost ; for instance, some Malay tribes in their simple theory of 
diseases are content to say that one kind of demon causes small-pox, another 
brings on swellings, and so on. . . . The savage theory of demoniacal pos- 
session has for its natural result the practice of exorcism or banishment of the 
spirit as the regular means of cure, as where, to select these from hundreds of 
instances, the Antilles Indians in Columbus's time went through the pretence 
of pulling the disease off the patient and blowing it away, bidding it begone 
to the mountain or the sea; or where the Patagonians, till lately, believing 
every sick person to be possessed by an evil demon, drove it away by beating 
at the bed's head a drum painted with figures of devils. 

" That such modern savage notions fairly represent the doctrines of disease- 
possession in the ancient world is proved by the records of the earliest civilized 
nations. The very charms still exist by which the ancient Egyptians resisted 
the attacks of the wicked souls, who, become demons, entered the bodies of 
men to torment them with diseases and drive them to furious madness. The 
doctrine of disease among the ancient Babylonians was that the swarming 
spirits of the air entered man's body, and it was the exorcist's duty to expel 
by incantations ' the noxious neck-spirit,' ' the burning spirit of the entrails 
which devours the man,' and to make the piercing pains in the head to fly 
away 'like grasshoppers' into the sky. ... No record shows the ancient 
theory more clearly than the New Testament from the explicit way in which the 



24 ETIOLOGY OR THE CAUSES OF DISEASE 

and the diseased condition is the result of the influence 
of some entity foreign to the patient, to something acting 

symptoms of the various affections are described, culminating in the patient 
declaring the name of his possessing demon, and answering in his person when 
addressed. The similarity of the symptoms with those which in barbarous 
countries are still accounted for in the ancient way may be seen from such 
statements as the following, by a well-known missionary (Rev. J. L. Wilson, 
' Western Africa,' page 207) : ' Demoniacal possessions are common, and 
the feats performed by those who are supposed to be under such influence are 
certainly not unlike those described in the New Testament. Frantic gestures, 
convulsions, foaming at the mouth, feats of supernatural strength, furious rav- 
ings, bodily lacerations, gnashing of teeth, and other things of a similar char- 
acter may be witnessed in both of the cases.' Among the early Christians 
the demoniacs or energumens formed a special class under the control of a 
clerical order of exorcists, and a mass of evidence drawn from such writers as 
Cyril, Tertullian, Chrysostom, and Minutius Felix shows that the symptoms 
of those possessed were such as modern physicians would class under hysteria, 
epilepsy, lunacy, etc. . . . Some theologians, while in deference to advanced 
medical knowledge they abandon the primitive theory of demons causing 
such diseases in our own time, place themselves in an embarrassing position by 
maintaining, on the supposed sanction of Scripture, that the same symptoms 
were really caused by demoniacal possession in the first century. . . . For 
our times this seems too like a discussion whether the earth was really flat in 
the ages when it was believed so, but became round since astronomers pro- 
vided a different explanation of the same phenomena. It is more profitable to 
notice how gradual the change of opinion has been from the doctrine of 
demon-possession to the scientific theory of disease, and how largely the 
older view still survives in the world. Not only in savage districts, but in 
countries whose native civilization is below the European level, such as India 
and China, the curious observer may still see the exorcist expel the malignant 
ghost or demon from the patient afflicted with fever, dizziness, frenzy, or any 
accountable ailment. . . . The unbroken continuance of the belief in medi- 
aeval Europe may be gathered from various works. . . . Even in the eigh- 
teenth century was published with ecclesiastical approval a regular exorcist's 
manual, the ' Fustis et Flagellum Dcemonum,' Auctore R. P. F. Hieronimo 
Mengo (1727), which among its curious contents gives instructions how to 
get the better of those cunning demons who hide in the bodies of men and 
vex them with diseases, and which are apt, when expelled, to take refuge in 
the patient's hair. The gradual shifting of opinion is marked by the attempt 
to reconcile the older demonology with the newer medicine. The argument, 
which appears among the early Christian fathers, is worked out most elabo- 
rately in that curious museum of demonology, the ' Disquisitiones Magicae ' 
of Martin Delrio, published as late as 1720. While inveighing against those 
physicians who maintain that all diseases have natural causes, this learned Jesuit 



DISEASES AND DEMONIACAL POSSESSION 25 

from or coming from the environment. Of any disease aris- 
ing from within, or due to any intrinsic or mechanical defect 
or derangement of an apparatus — such as faulty materials 
or construction — the savage has no conception. This 
idea requires anatomical information and the power to 
reflect from the merely objective point of view ; in other 
words, the modern mechanical and scientific attitude of 
mind, the objective rather than the subjective capacity. 
Even here, however, the cure was logically applied. Sav- 
age therapeutics accurately followed savage pathology. If 
the disease were due to the possession of the patient by 
a demon or demons, nothing could be more logical or 
better medical practice than to seek somehow to cast them 
out. Exhortations, drums, or anything likely to influence 
the demon constituted a proper materia medica. Most 

admits that men may be dumb, epileptic, or lunatic without being obsessed; but 
what the demons do is that, finding the dispositions of epileptics suitable, they 
insinuate themselves into them; also they attack lunatics, especially at full moon, 
when their brains are full of humors, or they introduce diseases by stirring 
up the black bile, sending blacks into the brain and cells of the nerves, and 
setting obstructions in the ears and eyes to cause deafness and blindness. 
Looking at the date of this celebrated work, we cannot wonder that in 
benighted districts of Europe the old diabolical possession and its accompany- 
ing exorcism may still now and then be met with, as in 1861 at Morzine in 
Savoy. The London Times, in November, 1876, contained an account of the 
casting out of devils by a priest in the Church of the Holy Spirit in Barcelona, 
during the preceding month. On one occasion, the patient, a young woman 
of seventeen or eighteen, lay on the floor before the altar, writhing in convul- 
sions, with distorted features and foaming at the mouth, while the priest 
carried on a dialogue with the devil, whom he addressed by the name of 
Rusbel, the fiend's answers being of course spoken by the voice of the frantic 
girl herself. At last a number of demons were supposed to come out of the 
patient's body, and such scenes were repeated for days in the presence of 
many spectators till a riot arose, and the civil authorities, intervening, put a 
stop to the whole affair. One of the last notable cases of this kind in England 
was that of George Lukins of Yatton, a knavish epileptic, out of whom seven 
devils were exorcised by seven clergymen, at the Temple Church at Bristol, on 
June 13, 1788.'— Tylor. 

..." Thy demon, that's thy spirit that keeps thee." 

— " Antony and Cleopatra." 



26 AETIOLOGY OR THE CAUSES OF DISEASE 

effective of all would be the voice of a master who should 
command their obedience and compel them to come out. 

It was even possible upon the demonic theory, crude 
and childish as it was, to have a legitimate " preventive 
medicine." "The very charms still exist by which the 
ancient Egyptians resisted the attacks of the wicked souls, 
who, become demons, entered the bodies of men to tor- 
ment them with disease and drive them to furious mad- 
ness." And we all know of survivals even to-day in the 
charms and amulets which are supposed to resist bad 
luck, and the more material horseshoe, rabbit's foot, horse- 
chestnut in the trousers pocket, etc., which shall ward off 
witches or disease from us or from our habitations. 

§ 2. — The Theory of the Four Humors 

Long before the period of the highest development of 
Greek civilization, the primitive or demonic theory of dis- 
ease had ceased to satisfy the minds of cultivated men. 
Many traces of it indeed remain in the Homeric time; 
but with the arrival of the age of Pericles we have as his 
contemporary Hippocrates, already called "the Great," 
and ever since known as the " Father of Medicine." And 
now, apparently, for the first time, we find " a clear recog- 
nition of disease as being equally with life a process gov- 
erned by what we should now call natural laws. . . . The 
actual science of the Hippocratic school was of course very 
limited. In anatomy and physiology little advance has 
been made, and so of pathology in the sense of an expla- 
nation of morbid processes or knowledge of diseased struc- 
tures there could be very little. . . . The dominating 
theory of disease was the humoral, which has never 
since ceased to influence medical thought and practice. 
According to this celebrated theory, the body contains 
four humors, — blood, phlegm, yellow bile, and black bile, 
— a right proportion and mixture of which constitute 



ANCIENT AND MEDI/EVAL THEORIES 27 

health ; improper proportion and irregular distribution, 
disease. It is doubtful whether the treatise in which this 
theory is fully expounded is as old as Hippocrates him- 
self ; but it was regarded as a Hippocratic doctrine, and 
when taken up and expanded by Galen, its terms not only 
became the common property of the profession, but passed 
into general literature and common language. Another 
Hippocratic doctrine, the influence of which is fortunately 
not even yet exhausted, is that of the healing power of 
nature." : Much of the language of this famous theory 
still lingers, as when we speak of a "bilious" condition, 
a " sanguine," "phlegmatic," or "melancholic" (black 
bile) temperament. It had the high merit under Hippo- 
crates of fixing attention upon natural rather than super- 
natural causes, upon the patient rather than demons. 2 

§ 3. — Roman, Arabian and Mediceval Theories of Disease 

We need not follow in detail the shifting opinions of 
mankind as to the true causes of disease between the time 
of Hippocrates (500 b.c.) and that of Sydenham. In the 
decline of Greek culture and the Alexandrian period no 
new ideas of importance were successfully advanced or 
long maintained. The theory of the four humors, with 
various modifications and under various forms, prevailed, 
and even in the hands of Galen during the Roman period, 
though expanded and highly elaborated so that it became 
the standard authority for many centuries, remained essen- 
tially the same. During the Dark Ages no important new 

1 J. F. Payne , M.D., on the " History of Medicine," Encyclopedia Bri- 
tannica, 9th ed., Vol. XVII, p. 800. 

2 " The four Galenical humors, viz., the blood which took its origin in the 
liver, the phlegm secreted by the pituitary gland, the bile by the gall, and the 
black bile by the spleen. From the mixture of these humors arose the four 
natural ■ temperaments ' : sanguine, in which the blood was predominant ; 
phlegmatic or pituitous; bilious or choleric; atrabilious or melancholic; and 
from the ill-mixture of these ingredients resulted dyscrasia and new morbid 
humors, such as produced scurvy, scrofula and gout." — Pye-Smith. 



28 ETIOLOGY OR THE CAUSES OF DISEASE 

ideas were introduced into Europe by the Arabian physi- 
cians, Avicenna and Rhazes; for these authors worked 
largely upon the foundations laid by Hippocrates and 
Galen, and their theories need not detain us. The period 
of scholasticism also yielded nothing in the theory of 
disease beyond the four humors, but only endless com- 
mentaries on Hippocrates and Galen similar in character 
to those in philosophy upon Aristotle. Even for some 
time after the revival of learning and the splendid period 
of the Renaissance, this very revival being in the hands 
of "medical humanists" led to a renewed respect for 
ancient authority, and more than ever Hippocrates and 
Galen were regarded as authorities while the theory of the 
four humors naturally held full sway. With Paracelsus 
(1480-1541), however, emphatic doubts began to be boldly 
expressed as to the sufficiency of the ancient theories. 
The study of anatomy in Italy in the sixteenth century 
under Vesalius, Fallopius, Fabricus and many others, 
followed as it was early in the seventeenth by Harvey's 
marvellous discovery of the circulation of the blood, to- 
gether with the general progress of knowledge, finally 
raised grave doubts in the best minds as to the true causes 
of disease, doubts which were powerfully supported by the 
occurrence in Europe in the fifteenth and sixteenth centu- 
ries of certain highly destructive epidemic diseases, some 
of them hitherto unknown and all quite inexplicable on 
the theory of the four humors. Meantime there arose 
two schools, called respectively the " iatro-physical " and 
"iatro-chemical," the former basing itself on physiology 
and mechanical explanations of disease, the latter on chem- 
ical or fermentative processes. " The intestine movement 
of particles," or "fermentation," was the essence of the 
latter, the application of physics and mechanics to the 
body that of the former. The name of Sylvius (1614- 
1672) is widely known in connection with the iatro-chem- 
ical school. These schools, however, were compelled to 



THEORIES OF THE RENAISSANCE 



29 



struggle not only each with the other but both with the 
ancient (Hippocratic) doctrines. 

§ 4. — The Theory of Sydenham 

Thomas Sydenham (1644- 1689), who has been called 
"the English Hippocrates," held as "his main avowed 
principle to do without hypothesis and study the actual 
diseases in an unbiassed manner." According to Syden- 
ham, " a disease is nothing more than an effort of nature 
to restore the health of the patient by the elimination of 
the morbific matter." This full recognition of a materies 
morbi was a distinct advance, and foreshadows the time 
when the materies morbi would itself be regarded as 
specific in specific diseases. Sydenham appears to have 
recognized the fact that there are specific diseases, but to 
have fixed his attention rather on specific remedies than 
specific causes. The latter were not fully recognized until 
after Pasteur's classic researches on the specific microbic 
ferments of the diseases of wine and beer (1860-1864). 
After Thomas Sydenham (d. 1689) "the reign of canonical 
authority in medicine was at an end, though the dogmatic 
spirit long survived." The philosopher John Locke was 
a close friend of Sydenham, and the following quotation 
from one of Locke's letters is noteworthy: "You cannot 
imagine how far a little observation carefully made by a 
man not tied up to the four humors (Galen), or sal, 
sulphur, and mercury (Paracelsus), or to acid and alkali 
(Sylvius and Willis), which have of late prevailed, will 
carry a man in the curing of diseases though very stub- 
born and dangerous ; and that with very little and common 
things, and almost no medicine at all." 

§ 5. — Theories of the Eighteenth Century 

The theories of disease in the eighteenth century reflect 
plainly the spirit of the times. On the one hand we find 



30 /ETIOLOGY OR THE CAUSES OF DISEASE 

views largely mechanical, physical and even astrological; 
and on the other, an opposing series more mystical, ani- 
mistic and even spiritualistic. As natural successors to 
Hippocrates, Galen and Sydenham, we find Boerhaave, 
Haller and Morgagni, while opposed to them and as 
natural successors to Paracelsus, Hoffmann, Stahl (author 
of the Phlogiston theory in chemistry) and Hahnemann, 
— all more or less supernaturalists. The labors of Boer- 
haave, Haller and Morgagni served to establish upon a 
sure foundation our present essentially physical and me- 
chanical views of constitutional disease (see pp. 1 1, 13), but 
shed very little light on the class of diseases now called 
" infections" (the fevers, etc.), which run a peculiar definite 
course and then disappear. But if these diseases baffled 
the naturalists of the eighteenth century, they were still 
less understood by the supernaturalists, of whom only one 
(Hahnemann) has succeeded in making himself felt in the 
nineteenth century by the perpetuation of a special " sys- 
tem " typical of the numerous "systems" of the eighteenth 
century. 

§ 6. — The Theory of Hahnemann 

" Hahnemann taught that disease is to be regarded as 
consisting especially of the symptoms of it as experienced 
and expressed by the patient, or as detected by the physi- 
cian; in other words, that the chief symptoms, or the 
'totality of the symptoms,' constitute the disease, and 
that disease is in no case caused by any material substance, 
but is only and always a peculiar, virtual, dynamic derange- 
ment of the health. 'Diseases' (Introduction to the 
1 Organon,' p. 17) 'will not cease to be spiritual dynamic 
derangements of our spiritual vital principle.' He says 
on page 3 of the ' Organon ' : ' For as far as the greatest 
number of diseases are of dynamic (spiritual) nature, their 
cause is therefore not perceptible to the senses ; ' and at 
page 18, referring to 'small-pox, a disease accompanied 



THEORIES OF THE EIGHTEENTH CENTURY 31 

by almost general suppuration,' he asks, ' Is it possible to 
entertain the idea of a material morbific matter being 
introduced into the blood ? ' He held that the psoric 
miasm, of which the itch is the outward and visible and 
comparatively harmless sign, was at the root of nearly all 
chronic disease, viz., of all chronic disease that was not due 
to syphilis or sycosis. ... In all countries the doctrine 
of homoeopathy is still without broad scientific recogni- 
tion. . . . Hahnemann despised any deep study of disease, 
and theorized about it instead. Had he carefully inquired 
into the nature and natural history of disease as Hippo- 
crates did, or as he himself inquired into the sensations of 
those who took infinitesimal doses, he would have done 
more for the world and his own reputation. Hahnemann 
was easily captivated by theories, but not very sound in 
his reasoning. But underlying all his system, as we have 
seen, was the idea that the causes of disease were impal- 
pable, immaterial, spiritual, dynamic. And this great 
foundation was rotten. Modern medicine is doing some 
of its best work in showing the material and the visible 
character of the causes of many of the commonest diseases, 
and suggests this in many cases where it has not as yet 
been demonstrated. The cause of many diseases is shown 
to be a living germ or particle which can be discerned 
under the microscope, can be carried on a lancet or in a 
tube and inserted under the skin so as to produce its pecul- 
iar disease. . . . The causes of other diseases are often 
not merely visible under a microscope, but coarsely visible. 
We have been lately told, on high authority, that to pro- 
duce certain forms of blood-poisoning one or two ounces 
at least of septic fluid are necessary. So with other forms 
of common disease. Alcohol does not destroy a liver or 
kidney in any dynamic or immaterial form, but in coarse 
quantities diligently repeated. The lead which paralyzes 
the painter's wrist is not a ' spiritual ' thing. It is an 
accumulation of matter in the wrong place, and enters his 



32 ETIOLOGY OR THE CAUSES OF DISEASE 

body in palpable quantities, and, what is more, can be 
recovered in similar quantities from his body. So with 
the uric acid or its salts in the blood of a person who has 
inherited his father's gout, and perhaps his port wine. It 
is not a ' spiritual ' affair at all, but can be demonstrated 
chemically and under the microscope. The itch, to whose 
mysterious workings Hahnemann attributed two-thirds of 
the internal diseases of the body, including mania, cancer, 
gout, etc., is easily demonstrated to be dependent on an 
ugly crab-like insect, which can be destroyed in a few 
hours with sulphur, when there is an end both of it and 
of the itch." 1 

§ 7. — Theories of the Nineteenth Century 

If the eighteenth century is noteworthy for its numerous 
" systems " of medical theory, the nineteenth is equally 
conspicuous for its distrust of "systems." This was due 
doubtless in part to the natural swing of the pendulum, but 
whatever the cause may have been, there was unquestion- 
ably, in the first part of the century, a wholesome distrust 
of all " systems " and a return to a study of the " natural 
history of disease," what has been called a "rational 
empiricism " serving as the basis of medical practice. 
This " return to nature " was powerfully stimulated and 
facilitated by the rapid contemporary development of 
physical science, and above all by the invention of the 
achromatic microscope objective between 181 5 and 1830, 
so that the compound microscope, which had been so im- 
perfect as to be almost useless, became about 1835 a 
powerful and altogether novel instrument. Almost imme- 
diately results of capital importance were reached, for in 
1837 an Italian investigator, Bassi, announced the dis- 
covery that rnuscardine, a contagious disease of silkworms, 
previously not understood, is really due to a parasitic 

1 J. Grey Glover, M.D., on " Homoeopathy," Encyclopedia Britannica, 9th 
cd., Vol. XII, pp. 126-129. 






THEORIES OF TO-DAY 



i 



fungus. Two years later the still more startling discovery 
was made by Schoenlein that favus, or " honeycomb " of 
the human scalp, a disease 1 long known, but never under- 
stood, is really due to a parasitic fungus growing at the 
roots of the hair. At almost the same moment botanists 
discovered that yeast, hitherto regarded as a mysterious 
" ferment," is also a microscopic fungus ; and the idea was 
boldly advanced that fermentation, which had long been 
held to be one of the causes of disease, was really due to 
microscopic fungi. The new microscope was also applied 
to the study of diseased tissue, and immediately disclosed 
ravages so coarse and obvious as to compel the idea of 
mechanical interference by palpable agents and to stimu- 
late further search not only for the footprints of disease, 
but for the mysterious makers of those footprints. Mean- 
time the applications of physics and chemistry to physi- 
ology by Johannes M tiller and Wohler, Marshall Hall and 
Liebig, were drawing attention to the mechanical and 
material aspects of living things and the modern concep- 
tion of the body as a physical mechanism was becoming 
more firmly established. The pathologists likewise were 
making extraordinary progress in their explorations of the 
dead, and reporting constantly fresh examples of mechani- 
cal disturbance or interference, so that by the middle of 
the nineteenth century our theories of constitutional disease 
as largely due to poor timber or poor construction or 
mechanical breakdown were finally and probably forever 
established. 

1 This is a rare affection of the scalp and body due to the presence of a 
fungus Achorion Schoenleinii. The disease was recognized and named by 
Bateman and figured by Alibert. But it was not till 1839 that Schoenlein 
published in Muller's Archiv the discovery that the yellow crusts of Favus 
were neither pustular nor sebaceous, but were composed of the mycelia and 
conidia of a parasitic fungus. Ringworm of the Scalp was only proved to 
depend on the presence of a cryptogamic parasite in 1844 by Malmsen, the 
Swedish microscopist. He named the fungus Trichophyton tonsurans. 
— Pye-Smith, I.e. 

D 



34 AETIOLOGY OR THE CAUSES OF DISEASE 

The case was different, however, with certain diseases, 
such as the fevers, which run a definite course and disap- 
pear. These remained still unexplained and inexplicable. 
But their solution also was at hand. The obscure phenomena 
of fermentation, as we have seen above, had been claimed 
to be closely connected with disease by the iatro-chemical 
school of the seventeenth century, and this suggestion had 
apparently never been wholly lost sight of, though it was 
eclipsed in the eighteenth century by the rapid development 
of physiology. Modern chemistry began to unfold itself 
toward the close of the eighteenth century, and by the 
end of the first half of the nineteenth century, when the 
achromatic objective had been perfected, fermentation 
had assumed in the hands of Liebig great popular impor- 
tance. 

In 1837 the first serious attempt was made to collect 
and study the vital statistics of England, and a classifica- 
tion of diseases became necessary. For this classification 
of the various causes of death the following was at first 
used : — 

(1) Epidemic, endemic and contagious diseases. 

(2) Sporadic diseases. 

(3) Evident external causes. 

Some years later we find instead the following classi- 
fication : — 

(1) Zymotic diseases. 

(2) Constitutional diseases. 

(3) Local diseases. 

(4) Developmental diseases. 

(5) Violence. 
In other words, those diseases previously called "epi 

demic, endemic and contagious" are now described as 
"zymotic"; and upon this term we may dwell somewhat 
at length. 

" The diseases of this class have been frequently spoken 
of as fermentations. . . . The property of communicating 












ORIGIN OF THE TERM "ZYMOTIC" 35 

their action, and affecting analogous transformations in 
other bodies, is as important as it is characteristic in these 
diseases, which it is proposed therefore to call, in this 
sense, 'zymotic.' A single word, such as 'zymotics,' 
is required to replace in composition the long periphrasis 
1 epidemic, endemic, and contagious diseases ' with a new 
name, and a definition of the kind of pathological process 
which the name is intended to indicate. . . . The early 
medical observers have directed attention to the analogies 
zymotic diseases have with combustion, fermentation, 
putrefaction, and poisoning. These analogies have been, 
to a certain extent, confirmed by the researches of modern 
chemistry. . . . This class includes fever, small-pox, plague, 
influenza, cholera, and the other diseases which have the 
peculiar character of suddenly attacking great numbers of 
people at intervals in unfavorable sanitary conditions. 
The diseases of this class distinguish one country from 
another, one year from another ; they have formed epochs 
in chronology, and, as Niebuhr has shown, have influ- 
enced not only the fate of cities, such as Athens and 
Florence, but of empires ; they decimate armies, disable 
fleets ; they take the lives of criminals that justice has not 
condemned; they redouble the dangers of crowded hos- 
pitals ; they infest the habitations of the poor, and strike 
the artisan in his strength down from comfort into help- 
less poverty ; they carry away the infant from the mother's 
breast, and the old man at the end of life ; but their direst 
eruptions are excessively fatal to men in the prime and 
vigor of age. Pestilence and famine have always ob- 
tained the special attention of governments ; and epidemi- 
cal maladies have a special claim now to the attention of 
the statist, inasmuch as by prophylactic methods, of which 
vaccination is an example, and by hygienic arrangements, 
the ravages of epidemics may be greatly diminished. They 
are more than other diseases under public control, and 
may be diminished to a large extent by sanitary measures. 



36 ETIOLOGY OR THE CAUSES OF DISEASE 

. . . New names are wanted to designate new groups of 
phenomena, and might perhaps be less equivocally desig- 
nated by letters of the alphabet ; but to assist the memory 
words have been employed which, by their etymology, will 
suggest the group. We do not, however, in any case 
accept the etymological sense as a definition or a descrip- 
tion of the group of causes which a name designates. 
Thus, parts of the body undergo a specific transformation 
in the diseases of the first class, and they have been desig- 
nated Zymotic Diseases (zymotici) in England, without 
any intention to imply that these diseases are fermenta- 
tions." 1 

In spite of Dr. Farr's care not to assume close simi- 
larity between fermentations and zymotic disease, 2 the 
proof of such similarity was, even as he wrote, about to 
be brought forward by Pasteur. 

§ 8. — The Germ Theory of Fermentation 

Alcoholic fermentation had been generally regarded as 
a purely chemical or a physical process until in 1838 
Cagniard de Latour and Schwann showed that the yeast 
which accompanies it is a living plant. Liebig met this 
discovery with scorn and ridiculed the idea that yeast 
was the cause rather than the consequence of fermenta- 
tion in an article which Huxley has well called the most 
remarkable that ever appeared in a sober scientific jour- 
nal. Nevertheless, though with many hindrances because 
of the powerful opposition of Liebig, it slowly became 

1 " Vital Statistics : A Memorial Volume of Selections from the Reports 
and Writings of Dr. William Farr," pp. 246, 249, 253. London, 1885. 

2 The reluctance of Dr. Farr to connect zymotic diseases with fermenta- 
tions was not exceptional, and was probably due in part to the strenuous 
opposition of Liebig to that view. In 1863, Sir Robert Christison, in an 
" Address on Public Health " before the Association for the Encouragement 
of Social Science in Edinburgh, said of zymotic diseases, " They are so called 
from the Greek zyma, signifying ferment, on account of a rather fanciful 
resemblance between their origin and the process of fermentation." 






PASTEUR'S STUDIES ON BEER AND WINE 37 

clear that the germ theory of fermentation is true, and that 
live yeast is the real "ferment" of the alcoholic fermen- 
tation. This biological theory was thoroughly and finally 
established by Louis Pasteur between 1857 and 1863, and 
almost immediately led to the germ theory of disease 
through its extension by him to the diseases of beer and 
wine, which he traced to micro-organisms other than ordi- 
nary yeast invading the fermentable liquid and interfering 
with the usual alcoholic fermentation by producing unde- 
sirable fermentations of their own. At once it became 
clear to Pasteur (and soon after to the world) that specific 
fermentations are caused by specific ferments ; and, more- 
over, that a disease of wine or beer may be, and often is, 
simply an undesirable fermentation produced by an invad- 
ing ferment or germ. 

§ 9. — The Germ or Zymotic (Ferment) Theory of Disease 

It could hardly fail to occur to any thoughtful person 
that if this were true for certain diseases of wine and beer, 
it might well be true also for certain diseases of animals ; a 
for if we consider step by step the course of any familiar 
fermentation and then do the same for any familiar infec- 
tious disease, we shall discover between them a remarkable 
similarity. For this purpose we may take the fermenta- 
tion of apple juice, or cider, and small-pox. The juice of 

1 " Les sciences gagnent toutes a se preter un mutuel appui. Lorsque, a la 
suite de mes premieres communications sur les fermentations, en 1857-1858, 
on put admettre que les ferments proprement dits sont des etres vivants, que 
des germes d'organismes microscopiques abondent a la surface de tous les 
objets dans Patmosphere et dans les eaux, que Phypothese d'une generation 
spontanee est presentment chimerique, que les vins, la biere, le vinaigre, le 
sang, Purine, et tous les liquides de Peconomie n'eprouvent aucune de leurs 
alterations communes au contact de Pair pur, la medecine et la chirurgie 
jeterent les yeux sur ces clartes nouvelles. Un medecin francais, le Dr. 
Davaine, fit la premiere application heureuse de ces principes a la medecine, 
en 1863." — {Pasteur.) "La Vie de Pasteur," par Rene Vallery-Radot, 
p. 390. Paris, 1900. 



38 ETIOLOGY OR THE CAUSES OF DISEASE 

apples is hermetically sealed and kept from exposure to air 
by the apple skin. In the making of cider this skin is 
broken, the juice is pressed out and of course exposed 
to the air, to dust, to the press, to the sides of the vessel 
which receives it, to the strainer through which it passes, 
etc. At first, and for some time, the juice is sweet, insipid, 
unfermented, but after some time it is plain that a change 
is going on. This change is called the "working" or 
active fermentation of the apple juice, and a closer exami- 
nation will show that it is accompanied by a slight rise of 
temperature or " heating " (which is a familiar phenomenon 
in many fermentations), as well as by obvious chemical 
changes resulting in the evolution of gas and the dis- 
appearance of sugar, in place of which alcohol makes its 
appearance, giving to the whole process the name of 
" alcoholic fermentation." The fermentation of any par- 
ticular portion of apple juice, however, is not indefinitely 
prolonged. On the contrary, after a comparatively short 
time the process comes to an end, the evolution of gas 
ceases, and rest supervenes. Since Pasteur's classical 
researches we know that what has really happened has 
been, first, the seeding of the apple juice by (wild) yeast ; 
second, the slow growth of this during the quiescent period ; 
third, its active growth and "working" during the time 
of obvious fermentation ; and fourth, its gradual cessation 
of activity during the final period. In the case of the 
infectious disease known as small-pox the history is usually 
as follows : A susceptible patient must first be exposed 
to the disease, perhaps by contact with a person already 
affected, perhaps with clothing, letters, food or other ma- 
terials handled by such a person. After such exposure 
there is for a time no marked change ; but because the dis- 
ease has been shown by repeated experience to be never- 
theless gradually developing, as judged by the result and 
certain obscure premonitory symptoms afterward recalled, 
physicians have unanimously agreed to name this the 



FERMENTATION AND INFECTIOUS DISEASE 



39 



period of incubation. Sooner or later, headache, malaise, 
and other troubles appear, the patient becomes seriously 
and obviously ill, a physician is called in, a rise of tempera- 
ture or fever is discovered, the eruption and other marks 
of small-pox appear, and the patient is plainly affected by 
active disease accompanied by every indication of profound 
disturbance and chemical change. But at last, if death does 
not supervene, recovery ensues, and the patient gradually 
becomes free from the disease by which he was tempo- 
rarily overcome. We may add that the barrel of apple juice 
can undergo the alcoholic fermentation only once, and that 
the small-pox patient likewise, as a rule, has the small-pox 
only once. If now we tabulate side by side, and in order, 
the principal phenomena of an alcoholic fermentation such 
as that of apple juice, and those of an infectious disease 
such as small-pox, we shall discover a remarkable similarity 
between them. 



A Fermentation 

(Apple juice) 

i. Exposure of the juice to air, 
dust, etc. 

2. Repose and then slow change. 

(Growth of the ferment.) 

3. Active fermentation or "work- 

ing. 1 ' Evolution of gas bub- 
bles, change of sugar to 
alcohol. Rise of tempera- 
ture. 

4. Gradual cessation of fermenta- 

tion. 

5 . No further liability to alcoholic 

fermentation. 



An Infectious Disease 

(Small-pox) 

1 . Exposure of the patient to in- 

fection. 

2. Incubation. (Slow and insid- 

ious progress of the disease.) 

3. Active disease. Eruption, dis- 

turbance of the usual func- 
tions. Rise of temperature 
or fever. 

4. Slow convalescence (or death). 

5. Immunity to small-pox. 



The striking analogy here shown suggests something 
more. It certainly justifies the suspicion of relationship, 
and shows well the natural fitness of the term "zymotic" 
(fermentative) for that class of diseases in which an anal- 
ogy so remarkable is manifest. 



40 ETIOLOGY OR THE CAUSES OF DISEASE 

In the next chapter we shall obtain further indications 
of close relationship between fermentation and disease. 
Meanwhile, we cannot fail to observe that as soon as it 
was shown by Pasteur that the phases of an alcoholic fer- 
mentation are due to the introduction, growth and chemical 
work of a living ferment (yeast) finding its way into the 
apple juice from the air, dust or the outer skin of the 
apple, it became easy and natural to suspect that small-pox 
and similar diseases are somehow caused by similar living 
ferments finding their way into the body of the patient. 
Thus the " germ" theory of fermentation naturally led to 
a " germ " theory of infectious disease ; and movement in 
this direction became almost irresistible when Pasteur 
soon after established a fact of the very first importance, 
namely, that the diseases of wine and beer are "germ " 
diseases, due to their invasion by, and the growth within 
them of, undesirable micro-organisms (bacteria or wild 
yeasts). 

General attention was now drawn to the subject, and the 
germ theory of disease became very widely known when 
Pasteur, hitherto a mineralogist, chemist and biologist, 
turned aside from his laboratory studies on the fermenta- 
tions of wine, beer, vinegar and milk, and, in response to 
an urgent call from the French government, began a per- 
sonal investigation of a widespread animal disease, which 
had hitherto baffled all inquiry. This was the famous 
" silkworm disease " of which his son-in-law, M. V.-Radot, 
has given us an admirable popular account. Inasmuch 
as this brilliant effort of Pasteur was one of the most 
important factors in drawing universal attention to the 
germ theory of disease, and inasmuch as it is in itself an 
inspiring example of a scientific grappling with disease, 
we may quote at some length Radot's graphic description, 
v as follows : — 






ZYMOTIC DISEASES OF BEER AND WINE 41 

§ 10. — Louis Pasteur and Infectious Diseases of Silk- 
worms * 

" The life of the population of certain departments in the South of 
France hangs on the existence of silkworms. In each house there is 
nothing to be seen but hurdles, over which the worms crawl. They are 
placed even in the kitchens, and often in well-to-do families they occupy 
the best rooms. In the largest cultivations, regular stages of these 
hurdles are raised one above the other, in immense sheds, under roofs 
of disjointed tiles, where thousands and thousands of silkworms crawl 
upon the litters, which they have the instinct never to leave. Great 
or small, the silkworm-rearing establishments exist everywhere. When 
people accost each other, instead of saying ' How are you ? ' they say 
* How are the silkworms ? ' In the night they get up to feed them or to 
keep up around them a suitable temperature. And then what anxiety 
is felt at the least change of weather ! Will not the mulberry leaves be 
wet ? Will the worms digest well ? Digestion is a matter of great im- 
portance to the health of the worms, which do nothing all their lives but 
eat ! Their appetites become especially insatiable during the last days 
of rearing. All the world is then astir, day and night. Sacks of leaves 
are incessantly brought in and spread out on the litters. Sometimes 
the noise of the worms munching these leaves resembles that of rain 
falling upon thick bushes. With what impatience is the moment waited 
for when the worms arrive at the last moulting ! Their bodies swollen 
with silk, they mount upon the brambles prepared for them, where they 
shut themselves up in their golden prisons and become chrysalides. 
What days of rejoicing are those in which the cocoons are gathered ; 
when, to use the words of Olivier de Serres, the silk harvest is garnered 
in ! . . . 

"In the epidemic which ravaged the silkworm nurseries in 1849, the 
symptoms were numerous and changeable. Sometimes the disease 
exhibited itself immediately. Many of the eggs were sterile, or the 
worms died during the first days of their existence. Often the hatch- 
ing was excellent, and the worms arrived at their first moulting, but 
that moulting was a failure. A great number of the worms, taking little 
nourishment at each repast, remained smaller than the others, having 
a rather shining appearance and a blackish tint. Instead of all the 
worms going through the phases of this first moulting together, as is 
usually the case in a batch of silkworms, they began to present a marked 
inequality, which displayed itself more and more at each successive 

1 " Louis Pasteur : His Life and Labors." By his Son-in-Law. Trans- 
lated by Lady Claud Hamilton. P. 127 et seq. N.Y., Appleton, 1885. 






42 ETIOLOGY OR THE CAUSES OF DISEASE 

moulting. Instead of the worms swarming on the tables, as if their 
number was uniformly augmenting, empty spaces were everywhere 
seen ; every morning corpses were collected on the litters. 

" Sometimes the disease manifested itself under still more painful 
circumstances. The batch would progress favorably to the third, and 
even to the fourth moulting, the uniform size and the health of the 
worms leaving nothing to be desired ; but after the fourth moulting the 
alarm of the husbandman began. The worms did not turn white, they 
retained a rusty tint, their appetite diminished, they even turned away 
from the leaves which were offered to them. Spots appeared on their 
bodies, black bruises irregularly scattered over the head, the rings, the 
false feet, and the spur. Here and there dead worms were to be seen. 
On lifting the litter, numbers of corpses would be found. Every batch 
attacked was a lost batch. In 1850 and 185 1 there were renewed fail- 
ures. Some cultivators, discouraged, attributed these accidents to bad 
eggs, and got their supplies from abroad. 

"At first everything went as well as could be wished. The year 
1853, in which many of these eggs were reared in France, was one of 
the most productive of this century. As many as twenty-six millions 
of kilogrammes of cocoons were collected, which produced a revenue 
of 130,000,000 francs. But the year following, when the eggs produced 
by the moths of these fine crops of foreign origin were tried, a singular 
degeneracy was immediately recognized. The eggs were of no more 
value than the French eggs. It was, in fact, a struggle with an epi- 
demic. How was it to be arrested ? Would it be always necessary to 
have recourse to foreign seed ? And what if the epidemic spread into 
Italy, Spain, and the other silk-cultivating countries ? 

" The thing dreaded came to pass. The plague spread ; Spain and 
Italy were smitten. It became necessary to seek for eggs in the Islands 
of the Archipelago, in Greece, or in Turkey. These eggs, at first very 
good, became infected in their turn in their native country ; the epi- 
demic had spread even to that distance. The eggs were then procured 
from Syria and the provinces of the Caucasus. The plague followed 
the trade in the eggs. In 1864 all the cultivations, from whatever cor- 
ner of Europe they came, were either diseased or suspected of being so. 
In the extreme East, Japan alone still remained healthy. 

" Agricultural societies, governments, all the world, were preoccupied 
with this scourge and its invading march. It was said to be some 
malady like cholera which attacked the silkworms. Hundreds of pam- 
phlets were published each year. The most foolish remedies were pro- 
posed, as quite infallible, — from flowers of sulphur, cinders, and soot 
spread over the worms, or over the leaves of the mulberry, to gaseous 
fumigations of chlorine, of tar, and of sulphurous acid. Wine, rum, 



AN INFECTIOUS DISEASE OF SILKWORMS 43 

absinthe, were prescribed for the worms, and after the absinthe it was 
advised to try creosote and nitrate of silver. In 1863 the Minister of 
Agriculture signed an agreement with an Italian who had offered for 
purchase a process destined to combat the disease of the silkworms, by 
which he (the Minister) engaged himself, in case the efficacy of the 
remedy was established, to pay 500,000 francs as an indemnity to the 
Italian silk cultivator. Experiments were instituted in twelve depart- 
ments, but without any favorable result. In 1865 the weight of the 
cocoons had fallen to four million kilogrammes. This entailed a loss 
of 100,000,000 francs. 

" The Senate was assailed by a despairing petition signed by thirty- 
six hundred mayors, municipal councillors, and capitalists of the silk- 
cultivating departments. The great scientific authority of M. Dumas, 
his knowledge of silk husbandry, his sympathy for one of the depart- 
ments most severely smitten, the Gard, his own native place, all con- 
tributed to cause him to be nominated Reporter of the Commission. 
While drawing up his report the idea occurred to him of trying to per- 
suade Pasteur to undertake researches as to the best means of combat- 
ing the epidemic. 

" Pasteur at first declined this offer. It was at the moment when 
the results of his investigations on organized ferments opened to him a 
wide career ; it was at the time when, as an application of his latest 
studies, he had just recognized the true theory of the manufacture of 
vinegar, and had discovered the cause of the diseases of wines ; it was, 
in short, at the moment when, after having thrown light upon the ques- 
tion of spontaneous generation, the infinitely little appeared infinitely 
great. He saw living ferments present everywhere, whether as agents 
of decomposition employed to render back to the atmosphere all that 
had lived, or as direct authors of contagious diseases. And now it was 
proposed to him to quit this path, where his footing was sure, which 
offered him an unlimited horizon in all directions, to enter on an 
unknown road, perhaps without an outlet. Might he not expose him- 
self to the loss of months, perhaps of years, in barren efforts ? 

" M. Dumas insisted. ' I attach, 1 said he to his old pupil, now 
become his colleague and his friend, i an extreme value to your fixing 
your attention upon the question which interests my poor country. Its 
misery is beyond anything that you can imagine.' 

" ' But consider, 1 said Pasteur, i that I have never handled a silk- 
worm. 1 

"'So much the better, 1 replied M. Dumas. ' If you know nothing 
about the subject, you will have no other ideas than those which come 
to you from your own observations. 1 

" Pasteur allowed himself to be persuaded . . . and on June 6, 1865, 



44 ETIOLOGY OR THE CAUSES OF DISEASE 

started for Alais. The emotion he felt on the actual spot where the 
plague raged in all its force, in the presence of a problem requiring 
solution, caused him at once to forget the sacrifices he had made in 
quitting his laboratory at the Ecole Normale. He determined not to 
return to Paris until he had exhausted all the subjects requiring study, 
and had triumphed over the plague. 

" One of the most recent and the most comprehensive memoirs upon 
the terrible epidemic had been presented to the Academy of Sciences 
by M. de Quatrefages. One paragraph of this paper had forcibly struck 
Pasteur. M. de Quatrefages related that some Italian naturalists . . . 
had discovered in the worms and moths of the silkworm minute cor- 
puscles visible only with the microscope. . . . This instrument had 
already rendered such services to Pasteur in his delicate experiments on 
ferments that he was fascinated by the thought of resuming it again as 
an instrument of research. . . . 

" In a few hours after his arrival he had already proved the presence 
of corpuscles in certain worms, and was able to show them to the Presi- 
dent and several members of the Agricultural Committee, who had 
never seen them. . . . 

" It was necessary to know if there existed the relation of cause and 
effect between the corpuscles and the disease. This was the great point 
to be elucidated. . . . 

" One of the first cares of Pasteur was to settle the question as to the 
contagion of the disease. Many hypotheses had been formed regarding 
this contagion, but few experiments had been made, and none of them 
were decisive. Opinions, also, were very much divided. . . . 

" But whatever the divergences of opinion might be, every one, at all 
events, believed in the existence of a poisonous medium rendered epi- 
demic by some occult influence. Pasteur soon succeeded, by accurate 
experiments, in proving absolutely that the evil was contagious. . . . 
All the disasters that were known to have happened in the silkworm 
nurseries, their extent and their varied forms, were faithfully reproduced. 
Pasteur created at will any required manifestation of the disease. . . . 

" For five years Pasteur returned annually for some months to Alais. 
The little house nestling among the trees, called Pont-Guisket, became 
at the same time his habitation and his silkworm nursery. . . . 



" All the obscurity which enveloped the origin of the diseases of silk- 
worms had now been dispelled. Pasteur had arrived at such accurate 
knowledge both of the causes of the evil and their different manifesta- 
tions, that he was able to produce at will either pebrine or flacherie. He 
could so regulate the intensity of the disease as to cause it to appear on 



PASTEUR'S PERSISTENCE AND VICTORY 45 

a given day, almost at a given hour. ... To triumph over this disease 
(pedrine), which was so threatening, Pasteur devised a series of obser- 
vations as simple as they were ingenious. . . . This process of pro- 
curing sound eggs is now universally adopted. . . . 



u But if Pasteur brought back wealth to ruined countries, if he had 
returned to Paris happy in the victory he had gained, he had also under- 
gone such fatigues, and had so overstrained himself in the use of the 
microscope while absorbed in his daily and varied experiments, that in 
October, 1868, he was struck with paralysis of one side. Seeing, as he 
thought, death approaching, he dictated to his wife a last note on the 
studies which he had so much at heart. This note was communicated 
to the Academy of Sciences eight days after this terrible trial. 

" A soul like his, possessing so great a mastery over the body, ended 
by triumphing over the affliction. Paralyzed on the left side, Pasteur 
never recovered the use of his limbs. To this day (1884), sixteen years 
after the attack, he limps like a wounded man. 1 ' 

§ 11. — Sir Joseph {now Lord) Lister and Infectious Dis- 
eases of Wounds. Sanitary {Aseptic) Surgery 

Stirred by the investigations of Pasteur, and reflecting 
upon their significance, Sir Joseph Lister, already an 
eminent surgeon of Edinburgh, became convinced that 
many wound diseases are probably infectious and, if so, 
preventable. Accordingly, he set to work, and by the 
use of antiseptic dressings, sprays, instruments, etc., soon 
established his thesis and paved the way for the modern 
practice of sanitary or aseptic surgery, which was not only 
the first-fruit, but is also hitherto the most brilliant of the 
triumphs, of the germ theory of infectious disease. By 
its aid surgery has been not only revolutionized but also 
vastly extended. Operations formerly dreaded are now 
done with perfect assurance and constant success. The 
operating rooms of hospitals are built and conducted 
almost solely with reference to the exclusion or control 
of those micro-organisms (germs) which are now univer- 
sally recognized as the principal enemies of the patient 
and the worst foes of the surgeon. 



CHAPTER III 

ON THE RISE AND INFLUENCE OF BACTERIOLOGY. TRANS- 
FORMATION OF THE ZYMOTIC INTO THE ZYMOTOXIC THEORY 
OF INFECTIOUS DISEASE 

" Within the world of life to which we ourselves belong there is 
another living world, requiring the microscope for its discernment, but 
which, nevertheless, has the most important bearing on the welfare of 
the higher life-world." — Tyndall. 

"In der Aussenwelt, welche die alltagliche Umgebung des Menschen 
bildet und den Gegenstand der hygienischen Forschung ausmacht, findet 
der aufmerksame Beobachter in weitester Verbreitung Organismen, die 
an der Grenze der Sichtbarkeit stehen, selbst fur das mit besten opti- 
schen Hiilfsmitteln geriistete Auge, die aber mit ihrer ungeahnt aus- 
gedehnten, tief eingreifenden Thatigkeit eine hochwichtige Rolle im 
Haushalt der Natur und im Dasein des Menschen spielen. Sie bewirken 
die Zerstorung lebloser organischer Substanz, ... sie erregen die ver- 
schiedensten Gahrungen und sind uns unersetzliche Hiilfsmittel zur 
Bereitung unserer gewohnten Nahrungs- und Genussmittel ; sie be- 
fallen andererseits unsere Culturgewachse als Parasiten, die ihren 
Wirthen Degeneration und Tod bringen ; sie veranlassen gelegentlich 
schwerste Erkrankungen bei niederen und hoheren Thieren, und selbst 
den Menschen bedrohen sie mit morderischen Epidemien." 

— Flugge. 

§ i . — The Achromatic Microscope Objective 

Reference was made in the last chapter to the influence 
of the newly discovered achromatic microscope objective 
upon the development of the germ theory of fermentation 
and its corollary the germ theory of disease. Its aid was 
also now being felt from a somewhat different direction, 
namely, from purely zoological and botanical studies of the 
lowest forms of life. Pasteur's studies on wine and beer> 

4 6 



EXPLORATION OF THE MICROSCOPIC WORLD 47 

on the "organized corpuscles" of the air, and on the dis- 
eases of wine, beer and silkworms, had pointed downward 
into the world of the " infinitely little " as the source of 
those " germs " of life which seemed so small and yet so 
potent in fermentation and disease. All eyes, therefore, 
were turned in that direction, and extreme interest and 
curiosity were felt to know all that could be learned of the 
lowest forms of life, popularly described as " germs." This 
interest and curiosity were intensified, no doubt, by the 
rise just at this time of Darwinism, which also pointed 
downward for the beginnings of organic species to equally 
mysterious microscopic and primitive " germs " of life. As 
a result of these various inquiries one group of micro-organ- 
isms or germs, the Bacteria, then only recently studied by 
botanists, and lately located in the vegetable kingdom, 
became and has ever since remained of the first impor- 
tance to sanitarians and aetiologists. 

§ 2. — Animalcula> Vibrionia, Bacteria 

The compound microscope is believed to have been 
invented about the middle of the seventeenth century, and 
micro-organisms, some of which were probably bacteria, 
were seen by Kircher (1650), figured by Leeuwenhoek 
(1680) and, because they were capable of motion, received 
as a group the name Thierchen or animalcula, i.e. " little 
animals " or " animalcules." The compound microscope 
of the seventeenth century, however, was a very poor 
instrument and that of the eighteenth century little, if 
any, better. The best evidence of these facts is that many 
microscopists actually abandoned the use of the compound 
microscope of the day, preferring the simple microscope 
of lower power but comparative freedom from aberrations 
to the compound instrument of the time with its colored 
and distorted images. We need not be surprised, there- 
fore, to learn that the microscopists of the eighteenth 



48 RISE AND INFLUENCE OF BACTERIOLOGY 

century made but small progress in the territory of the 
" animalcules." The first important and extensive advance 
upon the work of Leeuwenhoek was made a hundred and 
fifty years later, and with the aid of the newly discovered 
achromatic objective, by Ehrenberg (1838) and his con- 
temporaries. The vast horde of forms originally called 
" animalcules " had, it is true, by this time been separated 
into two or three main divisions, only one of which is of 
consequence to us, namely, the Vibrionia, a group of the 
infusorial animalcules ; and in 1850 the suspicion for the 
first time found expression that these are not all, or neces- 
sarily, animal forms, for in that year a young physician of 
Boston, Dr. Waldo Irving Burnett, read before the Amer- 
ican Association for the Advancement of Science a paper 
entitled "The Family of Vibrionia (Ehrenberg) not Animals 
but Plants." His proofs were unsatisfactory, but the 
idea steadily grew until in 1857 Nageli, the distinguished 
botanist of Munich, definitely and finally classified the 
Vibrionia as plants, giving to them the name of Schizo- 
mycetes — "fission plants." To show that the earlier 
names still prevailed for a time, however, we need only 
mention the fact that Pasteur in his earlier papers fre- 
quently refers to these forms as " infusorial animalcules " 
or " corpuscles." A long step forward was made when, in 
1872, Ferdinand Cohn, of Breslau, began the publication 
of a series of papers entitled " Investigations on Bac- 
teria." 2 From that time onward the word " bacteria " has 
largely replaced the term "germs" in England, America 
and Germany. In France the term " microbes " seems 
to be preferred, and much can be urged in its favor. A 
synonym for this is extensively used in Germany, Great 
Britain and America, namely, "micro-organisms." Both 
terms are useful as including animal as well as plant forms ; 
and all of these terms may be said to be partial modern 
equivalents of the older term " animalcules." All of them 

1 "Untersuchungen iiber Bacterien," Beitrage zur Biologie. 



GERMS, MICROBES, MICRO-ORGANISMS, BACTERIA 49 

include living "ferments " capable of producing profound, 
though often invisible, changes in organic substances, and 
of causing singly or in cooperation those mysterious pro- 
cesses called fermentation, putrefaction, decay and some- 
times infectious disease. The bacteria alone belong exclu- 
sively to the vegetable kingdom. 

§ 3. — The Foundations of Bacteriology laid by Louis 
Pasteur 

It has already been told in the previous chapter how the 
labors of Louis Pasteur served to establish the " germ " 
theory of fermentation and prepared the way for a "germ" 
theory of disease. His labors bore fruit also by laying for 
all time the secure foundations of what has since come to 
be a new branch of science, namely, bacteriology. Pasteur 
was not the first to use the microscope in studies on fer- 
mentation, but he was the first to employ careful culti- 
vations of the micro-organisms concerned, and special 
importance belongs to his constant attempts to secure 
" pure cultures " of yeast and other living ferments. It 
is true that he was compelled to rely altogether upon liquid 
cultivation, so that the actual purity of his cultures is open 
to some question ; but there is no doubt whatever that by 
his ingenious and successful use of these so-called " pure 
cultures" — which led him to the discovery of specific 
causative germs in certain specific diseases of wine and 
beer, as well as in normal fermentations, such as the acetic 
and lactic, not to mention the specific " corpuscles " of the 
silkworm diseases, — Pasteur earned the high privilege of 
being regarded as the " founder " of bacteriology. It may 
be well to state at this point, by way of anticipation and in 
order to avoid misunderstanding, that the honor of estab- 
lishing bacteriology as a science upon the foundation laid 
by Pasteur, belongs to Robert Koch, who, by proving (in 
1876) that bacteria are the cause and not the consequence 



50 RISE AND INFLUENCE OF BACTERIOLOGY 

of a particular disease (anthrax) and by introducing (in 
1 88 1 ) an indispensable method of cultivation — the method 
of "solid" as opposed to "liquid" cultures — raised bac- 
teriology from a previously dubious position to one of 
high honor among the biological sciences. 

§ 4. — Micro-organisms the Cause and not merely the 
Consequence of Disease 

The germ theory of disease was not without strenuous 
opponents. In particular, the objection was raised that 
there was as yet no evidence that the germs observed in 
any disease might not have been caused by the disease 
itself, they being the consequence and not the cause of it. 
This was really a sound and valid objection. It had been 
successfully raised by Liebig against Cagniard de Latour 
and Schwann, the discoverers of yeast as a living fer- 
ment, as early as 1839, an ^ had been silenced in the 
case of Pasteur's studies on fermentation only with diffi- 
culty and by means of his use of needle inoculations and 
practically pure liquid cultivations. It was now (1865- 
1875) urged with reason and with vehemence because 
many absurd claims were being made regarding the dis- 
covery of the " germs " of various diseases, based upon 
mere observation of microbes in the bodies of persons suf- 
fering from those disorders or else detected in their food 
or drink. In such a case it was entirely possible for any 
one to urge that the patient had first fallen ill and had then 
been invaded by the germs, the disease being primary and 
the germs purely secondary and adventitious. This view 
was forever disproved, and bacteriology for the first time 
established on a scientific basis by the splendid researches 
of Robert Koch upon splenic fever, or anthrax, between 
1875 and 1878. Koch was a young physician of Woll- 
stein, in Prussia, when he began his studies on anthrax. 
This disease is not rare in Germany, Russia and other 



CULTIVATION OF SPLENIC FEVER GERMS 51 

parts of Europe, and affects mainly cattle, sheep and 
horses, but also, at times, human subjects. On examining 
the bodies of cattle dead of anthrax, Koch found with the 
microscope (as Davaine in 1859 and others before him had 
found) minute rods or sticks in the blood and other organs, 
and especially in the spleen. To some observers this had 
seemed enough to prove that these were the " germs " of 
the disease ; but Koch did not rest here. Following the 
methods already employed by Pasteur in his researches on 
yeast, Koch transferred a needleful of blood or other tissue 
charged with the mysterious rods to a relatively large por- 
tion of the clear normal liquid which constitutes the aque- 
ous humor of the ox's eye. 1 After a few days, or even 
hours, the rods, being alive and able to grow in this liquid, 
had multiplied enormously, while the portion of tissue 
carried over with them being dead had not increased but 
rather diminished. From this first dish a needleful was 
now similarly transferred to a second large and fresh por- 
tion of aqueous humor, which was thus seeded in its turn. 
From this second a third was eventually seeded, and so 
on. A little reflection will show that at each transplanting, 
though many of the rods were carried over, very little, and 
always less and less, of the original tissue was transferred. 
Moreover, the rods transplanted soon included few or none 
of the original rods derived from the diseased animal, but 
only the innumerable descendants of these in more and 
more remote generations. It is easy to see that after a 
number of transplantings not only none of the original 
diseased tissue could have remained — those things only 
being represented that had the power of life, growth and 
reproduction, but also none of the original " germs." This 
method of cultivating the living plants — for the rods are 

1 If it be asked how he hit upon the use of this liquid, the answer is that 
such transparent liquids had often been used in the study of animal tissues 
(histology), being known, because of their occurrence normally in the animal 
body, as " normal " fluids. 



52 RISE AND INFLUENCE OF BACTERIOLOGY 

plants — was clearly a kind of horticulture, and it has be- 
come known as the method of liquid "cultures." It should 
not be forgotten that it was first used successfully (for yeast) 
by Louis Pasteur. If as a result of its use only one kind 
of micro-organism (yeast, bacterium) finally remains, such 
a culture is said to be " pure," or " a pure culture " ; pre- 
cisely as a wheat field free from everything but wheat 
would be a " pure culture " of wheat. Moreover, just as 
the ripe grains of wheat in a wheat field are not those which 
were planted but only their offspring, so the rods in Koch's 
cultures of the third or tenth generation were not those 
originally sown by the needle or directly derived from the 
diseased animals. But if the rods so derived really caused 
the disease known as anthrax, then their own offspring 
might reasonably be expected to have similar properties 
and powers, precisely as wheat grains have the properties 
of the seed wheat. Accordingly, Koch proceeded to in- 
oculate healthy susceptible animals with his pure cultures 
of anthrax rods, rightly thinking that if these were the 
germs of the disease they should be able to reproduce it. 
The result was perfectly conclusive : the inoculated animals 
promptly died of typical anthrax, and proof now existed, 
for the first time in the history of pathology, that a specific 
germ was and is the cause, and not merely the accompani- 
ment or the consequence, of at least one well-known speci- 
fic, infectious disease. 

An immediate result of this brilliant work of Koch was 
to give a fresh stimulus to the study of the bacteria, already 
in full cry since the beginning of the classic researches of 
Cohn, who, in 1875, added to his earlier results the highly 
important discovery that some bacteria can, and under 
certain circumstances do, produce spores which appear to 
be protective, highly tenacious of life, and very resistant to 
destruction by drying, heat, poisons, etc. Moreover, Koch 
not only readily discovered spores in the rods of anthrax, 
but also succeeded, as only a very few observers had done 



CRUCIAL TESTS ON LIVING ANIMALS 53 

before him, in finding on other germs — notably certain large 
spiral forms in ditch water — cilia or lashes in active motion 
and presumably locomotor in function. These he (for the 
first time, in 1877) even succeeded in photographing. 1 

§5. — A New Method of cultivating Bacteria and the 
Establishment of Bacteriology as a recognized Biologic 
Science by Robert Koch in 188 1. 

Bacteria were probably first discovered in the latter part 
of the seventeenth century by Kircher and Leeuwenhoek, 
as has been stated already, but it was not until 1857 that 
microscopists were able satisfactorily to classify them as 
plants, and definitely locate them in the natural system. 
Pasteur observed many of them, for example a lactic 
ferment, a vinegar ferment and certain disease ferments 
of wine, beer, etc., and his work on these ferments, as well 
as on yeast, and especially his use of the method of "pure" 
liquid cultures, constitutes the basis of the modern science 
of bacteriology, no less than that of the germ theory of 
disease. Pasteur is, therefore, undoubtedly entitled to be 
known as the founder of bacteriology. And yet, owing to 
the intrinsic and peculiar difficulties of the subject, but 
little headway was made in exact knowledge of the bacte- 
ria themselves, and bacteriology as a distinct science was 
not established until, in 1881, a new and vastly improved 
method of cultivating bacteria was introduced by Robert 
Koch. This method, while extremely simple, was yet so 
effective and so fruitful that it forthwith became indis- 
pensable to many researches in biology. 

The method of cultivation which immediately proved so 
valuable is familiar to all biologists and is known as 
"Koch's method of solid cultures." Up to 1881 all cul- 
tures of yeast or bacteria hitherto made had been " liquid " 
cultures, such as were invented and used so effectively by 

1 Cohn' 



54 RISE AND INFLUENCE OF BACTERIOLOGY 

Pasteur in his establishment of the germ theory of fer- 
mentation and the germ theory of disease. 

Koch himself had used only liquid cultures in his great 
work on anthrax published in 1876; and Lister, Cohn and 
a host of others who studied fermentation and diseases be- 
tween 1869 and 1880 had used exclusively liquid cultures. 
In all these cases, however, it was very difficult to secure 
pure cultures because of the easy mingling in fluid media 
(such as bouillon or other fermentable or putrescible liquids) 
of various kinds of microbes, especially if the latter, as often 
happened, were endowed with the power of independent 
motion and could swim about. It was only by working on 
the basis of chance, and inoculating many flaskfuls by 
single needlefuls, that pure cultures could be got. This 
was tedious, uncertain, unsatisfactory, and in the hands of 
any but experts almost sure to lead to wrong conclusions. 
Thus it happened that during the twenty years after Pas- 
teur began to use liquid cultures, progress in bacteriology 
was slow and uncertain. We shall now see why, on the 
contrary, in the same number of years since Koch began 
his use of " solid " cultures, bacteriology has advanced by 
leaps and bounds. 

The method of solid culture overcomes the worst defects 
of the method of liquid culture, namely, first, the promiscu- 
ous mingling of different kinds of bacteria, and also, sec- 
ond, the time and labor consequently required to secure 
" pure " cultures. In this method the bouillon, or other 
liquid medium in which bacteria will thrive, is simply 
thickened while hot with gelatine or some similar substance 
such as Irish moss or agar-agar, so that when cooled the 
mass becomes a soft, moist jelly, capable of being melted 
by a gentle heat and solidified at the temperature of an 
ordinary room. It will be apparent on a moment's re- 
flection that any bacteria or similar micro-organisms pres- 
ent in the liquid must also be present in the solid mass, 
but with this important difference of condition, viz., that 



DISCOVERY OF THE TUBERCULOSIS MICROBE 55 

whereas in the liquid they float or swim about promiscu- 
ously, and may become thoroughly intermingled, such is 
not the case in the solidified mass, in which each is brought 
to rest and held captive at some small distance at least from 
every other. Moreover, since the " solid " medium con- 
tains as abundant nutrients as the " liquid," the bacteria 
are firmly fixed in a solid which is at once their prison and 
their food. Accordingly, they continue to feed and multi- 
ply or reproduce, though each remains fixed at or very 
near the point where it was imprisoned. After a day or 
two, as a result of continued feeding and reproduction, 
microscopic heaps of bacteria are formed, which finally 
become visible to the naked eye as minute dots, and when 
still larger are known as "colonies." If the parent of 
the colony was, as is usually the case, a single isolated, 
individual bacterium, the colony, being composed solely 
of the descendants of this germ, will be a " pure " cul- 
ture, readily and immediately supplying the material for 
other pure cultures of the same species. The ease and 
the saving of time, the simplicity, certainty, and accuracy 
of the method are obvious. Its superiority to the method 
of liquid cultures caused its immediate adoption, and it 
speedily led to the establishment of bacteriology as a 
recognized biological science. 

Almost immediately the new science began to yield 
wonderful fruit, for in the next year (1882) the whole 
world was startled at the announcement by Koch of his 
discovery of the micro-organism of tuberculosis, a bacillus 
usually found in the sputum of patients suffering from 
pulmonary consumption, capable of cultivation on solid 
media outside the human body, and able to produce the 
disease when inoculated into healthy susceptible animals, 
such as guinea-pigs. This announcement caused a pro- 
found sensation all over the world ; but so general and so 
conclusive was the confirmatory testimony that, in a sur- 
prisingly short time, it was accepted, and is now a matter 



56 RISE AND INFLUENCE OF BACTERIOLOGY 

of history. The next year (1883) witnessed the discovery, 
also by Koch, of the micro-organism of Asiatic cholera, 
in this case not a true bacillus or rod, but a curved form ; 
hence at first described as a " comma" bacillus and after- 
ward as a spirillum or vibrio. One year more (1884) 
yielded the rich prizes of the bacillus of diphtheria and that 
of tetanus (lock-jaw), as well as new and careful studies 
by Gaffky, with the improved methods, upon the bacillus 
of typhoid fever which had been partially worked out 
previously by Eberth and Koch. Very much, of course, 
still remained to be done, not only in the search for the 
germs or living ferments of important and familiar dis- 
eases, but also in verifying the steps already taken ; but 
it is no exaggeration to say that within five years from 
the time of Koch's introduction of the method of solid 
cultures the new science of bacteriology had achieved 
a recognized and honorable position. Moreover, the zy- 
motic theory of infectious disease was now established, and 
the dreams of the iatro-chemists and of William Farr had 
come true. 

We shall next see how the theory of infectious disease 
as due to living ferments has been gradually further 
elaborated into a theory of ferment-poisons, or in other 
words transformed from a zymotic into a zymotoxic theory. 

§ 6. — How, precisely, do Living Ferments produce 
Disease ? 

A little reflection will show that there are several ways 
in which invading micro-organisms might conceivably pro- 
duce disease in the animal body; for example, (1) by 
mere physical obstruction, clogging the capillaries, veins and 
arteries, and interfering mechanically with the ordinary 
operation of the vascular and other mechanisms ; or (2) by 
chemical interference, such as (a) theft of food or other 
chemical compounds needed by the body, or (b) by the 



DISCOVERY OF VARIOUS DISEASE GERMS 57 

generation of substances harmful to the body and there- 
fore to be reckoned as essentially poisonous or " toxic." 
It is not necessary to do more than suggest these various 
possibilities inasmuch as it is now universally agreed that, 
while other influences should not be overlooked, the prin- 
cipal method of damage lies in the generation of toxic 
products {tQxins\ resulting from the operation of living 
ferments within or upon the organism. This will be more 
readily understood by returning for a moment to a con- 
sideration of the alcoholic fermentation. In the case of 
apple juice invaded by wild yeasts, it is indeed true that 
the yeasts multiply enormously and enough to cause a 
physical change, the turbidity of the liquid ; and also that 
sugar, a valuable food substance, disappears by the agency 
of the yeast. But the most striking phenomenon, and one 
which has been universally recognized as such, as is 
proved by the fact that this fermentation has long borne 
its specific name, is, that a new and toxic substance, 
alcohol, is generated during the fermentation. In a word, 
just as yeast may be considered the specific germ of the 
alcoholic fermentation, alcohol may be regarded as the 
toxic substance generated by it, i.e. alcohol may be re- 
garded as a toxin produced by yeast. 

We must hasten to remark, however, that the products 
of fermentation are not always or necessarily poisonous 
either in character or quantity, as may be seen in the case 
of the alcoholic fermentation just cited and in the vinegar, 
lactic and similar fermentations. It is "however interesting 
to observe that the character of the substances produced 
is in each case specific, — yeast producing alcohol, the 
anthrax germ producing anthrax poison or toxin, the diph- 
theria bacillus diphtherotoxin, the typhoid fever bacillus 
typhotoxin, the lock-jaw bacillus tetanotoxin, and so on. 
But if this be so, then this class of living ferments may 
easily do its damage by means of its products, which are 
harmful to the body just as poisons are, and the mystery 



58 RISE AND INFLUENCE OF BACTERIOLOGY 

of an infectious disease becomes no greater, and perhaps 
no other, than a mystery of toxicology, such as exists, for 
example, in the case of poisoning by opium, belladonna, 
strychnine, and similar vegetable poisons. It is by reason- 
ing of this sort, based upon numerous observations and 
experiments, that the modern theory of infectious disease 
has reached the point to which we have now obviously 
come, namely, that the true theory of infectious disease 
is not merely a zymotic or ferment theory, but rather a 
zymotoxic or ferment-poison theory. 

It is plain that the invading micro-organisms which pro- 
duce disease are essentially parasites, and that the germ 
theory of disease is a theory of parasitism. The term 
"zymotoxic" is here preferred to "parasitic" simply as 
being more definite and more precise. There can be but 
little doubt, however, that the growth of knowledge of 
parasitism materially aided the acceptance of the germ 
theory. Favus and muscardine have already been cited 
as early examples, and the discovery of trichinae in swine, 
and, in particular, the recognition that epidemics may be 
caused by these microscopic worms doubtless paved the 
way for a more speedy general acceptance of a parasitic 
or germ theory of infectious disease. To this aspect of 
the subject we shall return in the next chapter. 

§ 7. — Sefisins, Ptomaines and Toxins 

It has long been recognized that spoiled meat, fish and 
other animal foods are sometimes dangerous to eat, and 
the popular assumption has been that they contained some 
deadly poisonous substance. As early as 18 14, according 
to Woodhead, Burrows in England described such a poi- 
sonous substance in putrefying fish ; while Kerner, in 1820, 
described a poisonous alkaloid which resulted apparently 
from the decomposition of albumen, and resembled in its 
physiological action a substance found by him in poison- 



BACTERIAL OR FERMENT POISONS 59 

ous sausages. Kerner compared this with atropine, the 
alkaloid of belladonna, in its toxic effects. In 1856 Panum 
obtained from decomposing animal matter a characteristic 
product soluble in water or alcohol to which he gave the 
name "sepsin." No great attention, however, was paid 
to these substances until about 1870, when Selmi drew 
general attention to the subject, and gave to the so-called 
poisonous alkaloids the name " ptomaines," i.e. "cadav- 
eric " substances. Nencki and also Brieger soon obtained 
several of these from pure cultivations of bacteria, and 
since that time it has been generally recognized that it is 
easy to separate from substances which have undergone 
fermentation or putrefaction chemical compounds more or 
less characteristic of the fermentation or putrefaction in 
question. When these are poisonous, they are often de- 
scribed as ptomaines ; and the whole group is popularly 
known by this name, though it is obviously unfit for the 
purpose. Some writers have undertaken to apply the word 
11 leucomaines " to those similarly derived but harmless. 

A more recent terminology describes the poisonous 
products of fermentation or putrefaction as toxins, and 
applies no name to the non-poisonous products. As we 
shall soon see, the ideas advanced in this paragraph have 
received widespread attention, and must be regarded as of 
the highest importance on account of their necessary con- 
nection with the subjects of susceptibility and immunity 
upon which we must dwell in the next chapter. 

§ 8. — Transformation of the Zymotic Theory of Infectious 
Diseases into the Zymotoxic Theory of to-day. Recapitu- 
lation 

Enough has now been said to make it clear that the 
modern idea of an infectious disease is somewhat more 
than that of a fermentation or a case of parasitism. It 
is not merely that the body of the patient is invaded by 



60 RISE AND INFLUENCE OF BACTERIOLOGY 

germs ; our theory goes much farther than this and shows 
us the germs growing, dividing and multiplying in the 
body of the patient, while at the same time each carries 
on its individual metabolic existence, acting upon its im- 
mediate environment, drawing to itself foods, and reacting 
by setting free the special products of its vital activity. 
It is not enough to suppose that the micro-organisms in 
question mechanically obstruct or physically disturb the 
delicate machinery of the living organism in which they 
multiply. The symptoms of infectious disease are rather 
those of toxic actions, actual poisonings of the body, 
accompanied by chills, fever, delirium and other symptoms 
of a profound disturbance. Moreover, the phases of infec- 
tious disease — the slow onset, the active illness, the recov- 
ery and the subsequent immunity — are all readily explained 
upon the modern theory of zymotoxic action. The slow 
onset is apparently due to the limited infection and the 
time required for the growth of the germs. The gradual 
increase of severity keeps pace with their multiplication 
and activity. The height of the disease corresponds to 
the height of their development. Its abatement to their 
decline. The subsequent immunity perhaps to the habitu- 
ation of the organism to their poison. The subject of 
immunity, however, is by no means well understood. It 
will be more fully considered in the next chapter. 

§ 9. — Objections to the Germ Theory 

The principal objection to the germ theory was and is 
that already referred to as met and overcome by Koch, 
viz., that germs may be seemingly the consequence, not 
the cause, of disease. Another objection is that in certain 
diseases the most careful search has failed thus far to re- 
veal causative micro-organisms. The answer to this latter 
is simply that in the absence of all positive evidence of 
the true cause of disease we are at liberty to choose the 



THE ZYMOTOXIC THEORY OF DISEASE 6l 

most likely working hypothesis, and no hypothesis has yet 
been found for any infectious disease more reasonable or 
more probable than the germ theory. 

"A great scientific theory has never been accepted with- 
out opposition. The theory of gravitation, the theory of 
undulation, the theory of evolution, the dynamical theory 
of heat — all had to push their way through conflict to 
victory. And so it has been with the germ theory of com- 
municable diseases." 1 

1 Tyndall, Essay on "Louis Pasteur, His Life and Labors." 



CHAPTER IV 

SANITARY ASPECTS OF THE STRUGGLE FOR EXISTENCE. 
PARASITISM. HEALTH AND DISEASE IN TERMS OF GEN- 
ERAL BIOLOGY. VITAL RESISTANCE, SUSCEPTIBILITY AND 

IMMUNITY 

" Nothing is easier than to admit in words the truth of the universal 
struggle for life, or more difficult — at least I have found it so — than 
constantly to bear this conclusion in mind." 

" Let it also be borne in mind how infinitely complex and close- 
fitting are the mutual relations of all organic beings to each other and 
to their physical conditions of life." 

— Darwin. " The Origin of Species." 

§ I. — Sanitary Aspects of the Struggle for Existence 

In the preceding chapters stress has been laid on the 
potency of the agents of disease proceeding from the en- 
vironment. This, however, is only one aspect of the 
matter. In order that living ferments or their poisons 
shall be effective, there must be a susceptible subject upon 
which they can act. Thus it comes to pass that in any 
zymotic disease the energy and virulence of the attacking 
agents are virtually pitted against the resistance of the 
patient, and a struggle ensues which may be, and often 
is, on one side or on both sides a veritable struggle for 
existence. In this case the struggle is between organism 
and organism, between man and microbe. In "The 
Origin of Species " Darwin, in dealing with the struggle 
for existence, dwells chiefly upon similar struggles of 
living things one with another, and it is this aspect of 
the subject which is still most often emphasized. For the 

62 



THE PARABLE OF THE SOWER 63 

hygienist, however, the struggle for existence means not 
only competition and battle and their consequences, not 
only the struggle of organism with organism, but also 
the broader struggle of the individuals with their whole 
environment. In the familiar parable of the sower we 
have a vivid picture of such a struggle for existence in 
the case of certain seeds : — 

" Behold, a sower went forth to sow ; And when he 
sowed, some seeds fell by the wayside, and the fowls 
came and devoured them up : Some fell upon stony places 
where they had not much earth ; and forthwith they sprung 
up, because they had no deepness of earth : And when 
the sun was up, they were scorched ; and because they 
had no root, they withered away. And some fell among 
thorns ; and the thorns sprung up, and choked them : But 
others fell into good ground, and brought forth fruit." 

In this parable both aspects of the struggle for exist- 
ence are dwelt upon : first the struggle of organism with 
organism, namely, of seeds with birds and with thorns ; 
and, second, of organism with lifeless environment, namely, 
with stony places, scorching sun and good earth. A 
similar breadth of view is required for the student of sani- 
tary science who seeks to gain a philosophic knowledge 
of the nature of disease; for disease may be the conse- 
quence not merely of organism struggling with organism, 
but also of organism struggling with lifeless environment. 
It is perhaps most often the result of both hostile organism 
and unfavorable lifeless environment acting together upon 
the human mechanism. Of the struggle of organism 
with organism parasitism affords a familiar and instruc- 
tive example. 

§ 2. — Parasitism and Infectious Disease 

Some recognition of what is now known as parasitism 
must have occurred very early in the history of the human 



64 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

race. It is exemplified, for example, in the case of the 
gourd which grew up and sheltered Jonah while he impa- 
tiently waited for the destruction of Nineveh, inasmuch 
as a -worm was sent in the night to feed upon and destroy 
the gourd ; and it is said that Pliny was familiar with 
the parasitism of the mistletoe. The word " parasite," 
however, arose in a different connection and was only 
recently applied to plants and the lower animals, having 
been apparently first used for a person who unbidden eats 
beside, or at the table of, another, and therefore, of course, 
lives at his expense. A few cases of parasitism, such as 
that of the mistletoe, were recognized very early because 
they were so conspicuous that they could not readily be 
overlooked. The well-known lines of Swift 1 testify unmis- 
takably to a recognition of the same phenomenon. For 
the most part, however, parasitism remained comparatively 
unrecognized until the introduction of the compound micro- 
scope revealed its almost universal prevalence. 

Parasitism is now known to be one of the commonest 
features of the struggle for existence, and it is not neces- 
sarily, as it is often supposed to be, an abnormal and 
strange development — at least in its beginnings. If, in 
the search for food, a plant or animal happens to come in 
contact with and feed upon another, it may easily result 
that it shall gain great profit thereby, though if this habit 
becomes so extended as to lead to the destruction of the 
host, the parasite itself may also perish. It is not difficult 
to suppose that parasitism may have arisen from sapro- 

1 " So, naturalists observe, a flea 

Has smaller fleas that on him prey; 
And these have smaller still to bite 'em. 
And so proceed ad infinitum" 
Of which a more popular, alliterative and generalized version is, — 

" Big bugs have little bugs 
Upon their backs to bite 'em; 
And little bugs have lesser bugs, 
And so ad infinitum" 



MICROBES SOMETIMES PARASITES 65 

phytism, in which plants or animals feeding upon dead or 
waste organic matters happened to become attached to 
living plants or animals, and it is easy to see how, under 
these circumstances, great advantage might accrue to the 
saprophyte. It is even possible to imagine how the ranks 
of parasites, thinned by the destruction of their hosts, or 
otherwise, might continually be recruited from among the 
saprophytes. 

The somewhat extended discussion of the germ theory 
of fermentation and disease in the previous chapter should 
not lead the reader to overlook the fact that many of the 
micro-organisms which are the prime movers of fermenta- 
tion and infectious disease must from another point of view 
often be regarded as parasites. The parasitic fungi have 
long been known in special cases to penetrate the tissues of 
their host precisely as microbes may "invade" the animal 
body. It has also been known that in doing this some 
solvent reagent was secreted by the fungus, and experi- 
ments have shown that it is possible to separate from par- 
ticular fungi substances which will corrode and destroy 
vegetable tissues. It thus appears that a close analogy is 
discoverable between the toxins or poisonous products of 
disease germs and these solvent reagents or tissue-poisons. 

It is customary to speak of the infectious diseases as 
essentially parasitic in their character, the disease germs 
being the parasites, and the organisms affected their hosts. 
This point of view is not only common, but exceedingly 
useful, for it places these diseases in the same category 
with certain well-known phenomena of parasitism (or sapro- 
phytism), and makes them thereby the more readily com- 
prehensible. The sanitarian in particular has reason to 
value this interpretation of infectious disease inasmuch as 
prevention of parasitism is, in theory at least, a compara- 
tively simple matter, namely, the destruction of the parasites 
in question and their control in the environment. When it 
comes, however, to an examination of the precise nature of 



66 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

the parasitism involved in infectious disease, we shall find 
it often necessary to regard the germs as parasites produc- 
ing chemical change and doing damage by the chemical 
changes which they effect, or the chemical bodies which 
they produce, rather than by the theft of food substances 
which is the more ordinary characteristic of parasitism. 

The germ theory is sometimes thus described as the 
parasitic theory of disease, and has also been called the 
"particulate" theory because the micro-organisms con- 
cerned are obviously material particles. This latter desig- 
nation is of value chiefly as emphasizing the reality of 
the materies morbi, or the fact that the causes of infectious 
disease are material particles and not merely immaterial 
conditions such as dynamical derangements of spiritual 
vital principles. The reader will be the better prepared 
to recognize the validity of the former term — the parasitic 
theory — if he will remember that just before the germ 
theory had taken definite shape two diseases, namely, 
muscardine in silkworms and fav us or honeycomb of the 
human scalp, had already been proved to be due to para- 
sitic fungi (see Chapter II, p. 32). Powerful support for 
a parasitic theory of disease had also been accumulating 
during the time of the growth of the germ theory of fer- 
mentation and disease, especially in connection with a 
terrible disease of man hitherto unsuspected, but by that 
time definitely known, namely, the disease caused by 
the parasite called the pork-worm {Trichina spiralis) and 
known as trichinosis. This disease is of special interest 
to sanitarians, inasmuch as the parasites which unquestion- 
ably produce it, while very minute are still scarcely to be 
called micro-organisms, and yet are so small that for a long 
time they escaped the detection which tapeworms, stomach- 
worms, etc., readily encountered. They thus form an 
interesting connecting link between the invisible micro- 
organisms and the coarsely visible tapeworms, etc., and the 
smaller fungi. (Cf. pp. 293, 296.) 



THE "PARASITIC" THEORY OF DISEASE 6? 

The whole matter may perhaps be summed up as fol- 
lows : from the widest point of view infectious diseases 
in common with all others are important and complicated 
phenomena in the universal struggle of organisms for 
existence. From a somewhat narrower point of view they 
are often to be regarded as cases of parasitism, the disease 
germ being the parasite and the organism affected being 
its host. From a still narrower point of view, and examin- 
ing the details of the struggle, the process appears to be 
essentially " toxic," the host being damaged by the para- 
site (or saprophyte) not so much by theft of material as by 
the products of its metabolic activity, namely, by chemical 
poisons known as " toxins." 

§ 3. — The Lifeless Environment and Disease 

Any extended treatment of this subject would be beyond 
the province of a work like this, since such a discussion 
belongs rather to hygiene than to sanitary science. Nev- 
ertheless, the student of sanitary science cannot neglect 
the influence of the lifeless environment as a powerful 
factor in the causation and modification of infectious disease, 
even when it is not the principal factor. In such disease, 
for example, the time, the occurrence, the duration and 
even the energy of the attack, may be profoundly influ- 
enced by external environmental conditions such as season, 
temperature, dryness or light. We may, therefore, with 
advantage, consider somewhat carefully the relations be- 
tween organisms and their environments, whether living 
or lifeless, before passing on to the more recondite sub- 
jects of susceptibility, vital resistance and immunity. 

In addition to a comprehension of the fact that the living 
organism is essentially a delicate physical mechanism, the 
student requires an adequate knowledge of what is meant 
by the terms " organism " and " environment," and with this 
a recognition of the significance of the actions, reactions 



68 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

and interactions which necessarily go on between organ- 
isms and their environments. 

In the language of biology an organism is a limited mass 
of living matter occupying a definite position in space and 
time. It is bounded on all sides by material substances, — 
earth, air, water, etc., — by which it is acted upon, and upon 
which it acts in return, and, on the whole, these actions and 
reactions are equal, though in opposite directions. Those 
portions of the material universe which thus act upon the 
organism are called its "environment," and a little reflec- 
tion will show that while it is the nearer portions which are 
most closely concerned and are, therefore, the most con- 
spicuous parts of "the environment," no part, in theory at 
least, is so remote as to have no influence. The whole 
material universe may be — must be — divided for any liv- 
ing thing into two parts, namely, that thing and its envi- 
ronment : the individual on the one hand, and the rest of 
the universe on the other, — very much as the ancient and 
mediaeval philosophers regarded man on the one hand as 
" microcosm " and the rest of the universe as " macrocosm." 
Biology teaches that if we would comprehend the doings of 
living things we must begin by taking this point of view. 
Viewed from this standpoint mankind becomes a host of 
masses of matter each bounded by the rest of the material 
universe, with which it must deal so long as it continues to 
live, and to which, no matter how prolonged the struggle, it 
must finally surrender. From the environment each must 
derive whatever of matter and energy it gains, and to it 
it must return whatever it loses. It may be profoundly 
affected by heat or cold, by lightning or earthquake, by fire 
or tempest ; and it may, on its part, react upon its environ- 
ment and displace the air by buildings or balloons, the sea 
by ships, the earth by mines or tunnels, or fire by incom- 
bustible substances. Every tree that lifts its branches 
into the aerial ocean reacts upon the atmosphere and, like 
every animal that burrows into the earth or builds its. 



ORGANISMS AND ENVIRONMENTS 69 

house or its nest in the air, reacts upon its environment. 
The encroachments of the sea may be resisted or overcome 
by dikes, of the wind by shelters, of the sunshine by 
shade. Everywhere in nature — and in man as a part of 
nature — we find actions and reactions incessantly going 
on, and these in the long run consist essentially of ex- 
changes of matter and of energy or of both, between 
masses of matter and their environments. 

§ 4. — Health and Disease in Terms of General Biology 

Life has been defined as "the continuous adjustment of 
internal to external relations," and health might be de- 
fined on these terms as the normal state and performance 
of this adjustment. Disease would then be some serious 
disturbance or grave departure from this normal state or 
performance, and might conceivably be due to (1) a 
failure of the intrinsic powers of adjustment ; or (2) some 
external condition so severe or unusual that the usual 
adjustment was impossible ; or (3) to a combination of 
these factors. From what was said in the first chapter 
(p. 12) it is clear that a failure of the mechanism itself to 
do its part, a failure of the intrinsic powers, such, for 
example, as old age effects, produces a constitutional dis- 
turbance or disease ; while external conditions, so hard or 
so unusual as to be met with difficulty or perhaps not at 
all, may well give rise to a disturbance or disease essen- 
tially environmental in its origin ; and the combined 
effect of imperfect mechanism or imperfect internal ad- 
justment with external relations difficult to deal with 
might lead to diseases seemingly environmental, but really 
no less truly constitutional in origin. A very little reflec- 
tion will show that to avoid disease and to forestall its 
effects there are required: (1) Mechanisms as capable as 
possible of adjustment to external relations, unfavorable 
as well as favorable. (2) Environments (external rela- 



yo THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

tions) to which the mechanism may readily adjust itself, 
or making as small demands as possible upon its powers 
of adjustment. 

Of these two factors the former is on the whole far the 
less under our control at present. The mechanism may in- 
deed, as a rule, be strengthened by good air, good food, rest 
and other favorable conditions ; it may be weakened by bad 
air, bad food, fatigue and other unfavorable conditions ; so 
that it shall adjust more, or less, successfully its internal to 
any external relations. But while so much is unquestion- 
ably true, and while efforts looking in this direction lie at the 
basis of all sound hygiene and constitute one of its proper 
functions, it is still true that the external relations to which 
the internal relations of the mechanisms must be adjusted, 
are much more largely under our control. In other words, 
it is to a great extent within our power (in theory at 
least) to provide environments or external relations to 
which almost any living mechanism should be able to 
adjust its internal relations; or, conversely, an environ- 
ment so unfavorable that few if any could possibly be 
able to adjust themselves to it. 1 



§ 5. — Three Principal Sanitary Conditions or States of 

Relation 

In actual life all these various conditions are readily 
observed. We find some persons so robust — that is to 
say, with mechanisms so capable of adjustment to external 

1 " The man who lives to the age of a hundred years and who, during that 
time, suffers no pain, and is continually able to make use of the powers pecul- 
iar to his age, would by universal testimony be regarded as an example of 
health ; yet even the life of such an one would not always be at its best ; and 
health, like every other such name, is to be used in a relative sense. Into the 
life of the healthiest man disorders must frequently enter. Absolute health 
is an ideal conception, as the line of the mathematician, the ether of the 
physicist, and the atom of the chemist." — T. C. Allbutt, "System of Medi- 
cine" I, xxii. 



SANITARY PARADOXES 



7 x 



relations of whatever kind — that nothing seems to daunt 
them. They work hard, eat poor food, live in bad air 
and seemingly disobey all the rules of hygienic living, and 
yet possess apparently perfect health. Conversely, others 
surrounded by every sanitary contrivance, well fed, well 
housed and tenderly cared for, sicken and die in an envi- 
ronment apparently the most absolutely favorable. And 
finally, in the same community, are many who thrive as 
long as their external relations are good and easily dealt 
with (" favorable "), but who suffer just as soon as these 
become difficult to deal with (" unfavorable "). 

Furthermore, these groups are by no means fixed and 
invariable, but rather constantly subject to change both as 
to membership and mass. A period of unusual environ- 
mental severity of climate, temperature, infection, finan- 
cial or political buoyancy or depression, may promote or 
reduce from one rank to another, with the consequence not 
only of numerous changes in actual sanitary conditions in 
individuals, but even extensive improvement or deteriora- 
tion in the average public health of a community. Of 
this a good example is some effective change in external 
relations, such as a financial panic, causing anxiety, loss of 
employment, increased exposure, poorer feeding, loss of 
sleep, etc., but perhaps the best example is one in which a 
novel and direct action proceeds from the environment, 
unknown, it may be, until its work is done. Such a pro- 
found change in the external relations of an entire com- 
munity occurs when some epidemic, unsuspected, falls 
upon an entire city or town. There are on record many 
cases of this kind, some of which are described in the 
eighth chapter. If, for example, a public water supply 
becomes contaminated with the germs of an infectious 
disease such as typhoid fever, the general standard of 
health in the community using it will be lowered, the weak, 
as a group, will, on the whole become weaker, the strong, 
less strong, and some of each group will perish altogether 



72 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

who would have lived longer if the infection had not 
reached them. 

The explanation of these three great groups — which 
we may call " the robust " or " the strong," " the well but 
not strong," and "the feeble" or "weak" — is simply 
that there are actually corresponding groups of organisms, 
or mechanisms, in every community. The " strong " are 
those endowed by nature, by inheritance, or it may be to 
some extent by training, with superior vital machinery. 
" The well but not strong " are similarly provided with 
machinery either poorer in quality or less successfully put 
together, while the " weak " or " feeble " are those hav- 
ing vital mechanisms so delicate in fibre or adjustment as 
to be always in need of attention or repair, even under 
ordinarily good conditions. It will be observed that no 
place is here left for those organisms which are altogether 
wanting in the power of " continuous adjustment of inter- 
nal to external relations." Such are those that perish, — 
some, before they are born ; some, vainly trying at birth to 
catch the first breath of life in order themselves to effect 
an oxygenation of their blood, hitherto provided for from 
the mother, from the novel atmospheric ocean in which if 
anywhere they must henceforward live; some, later, in 
that struggle for existence which compels them to deal 
with bad food, or exposure, or infection, or with sorrow 
or shame. Few, comparatively, are able to adjust their 
internal to their external relations so successfully as to 
reach the familiar threescore years and ten ; fewer still 
the fourscore years; and we have the authority of the 
psalmist that in the latter case it is only "by reason of 
strength " that the goal is reached : favorable environ- 
ments — favorable external relations — alone are not suffi- 
cient. The power of adjustment of internal relations is 
equally indispensable. 



THE STRONG AND THE WEAK 73 

§ 6. — Practical Importance of these Considerations 

The practical importance of these considerations is im- 
mense. Any one who deals chiefly with those more violent 
changes in the environment which produce great destruc- 
tion in a relatively short space of time is tempted to mini- 
mize the importance of forces acting more slowly over 
longer periods. The epidemiologist, for example, after 
witnessing the conspicuous effects of an outbreak of dis- 
ease affecting a whole community through impure food or 
drink, is strongly tempted to overlook the relatively remote 
effects of ordinary filth or foul air. And these are in fact 
far less striking, even when discoverable at all. But yet 
there is reason to believe that even quantitatively con- 
sidered they may do quite as much or even far more harm 
in the long run, for the great epidemics come seldom, 
affect a small number only, and pass quickly ; while filth 
and bad air act unfavorably upon a much larger number 
for a much longer time, keeping them frequently and per- 
haps constantly weakened, and enhancing always their 
susceptibility to specific disorders. 

Nor must we allow ourselves to be deceived by appear- 
ances. It is true that abounding health is often exhibited 
by those dwelling in most unwholesome places, and that 
many who never wash outlive many who do. But this does 
not mean that sanitary dwellings are superfluous, or that 
bathing is a waste of time. Nothing is plainer in sanitary 
science, as in human experience, than that " Cleanliness is 
next to Godliness," and that on the whole the first external 
condition of health is cleanliness. On looking closely we 
shall find that the cases observed are exceptional, or that 
the persons in question are the strong survivors of many 
now dead among whom they represent the survival of the 
fittest ; or that they have really bathed in their own sweat, 
thus shedding off the outer skin and with it much dirt and 
many micro-organisms ; or finally, that although the sur- 



74 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

viving younger members of the family may seem hale and 
hearty, the elders, while still young in years, show the 
effects of the struggle for existence and often break down 
or succumb to disease before their natural time. 

Darwin somewhere refers, more in sorrow than in anger, 
to those persons who have failed to understand him because 
they were utterly unable to appreciate the cumulative ef- 
fects of small changes acting over long periods of time. 
The sanitarian needs constantly to be warned against the 
neglect of small and seemingly insignificant factors of 
disease in the form of unfavorable conditions which by 
their prolonged action and cumulative effects may produce 
great results. 

§7. — Vital Resistance and Susceptibility 

The reader is now in a position to understand in its 
general aspects the term " vital resistance." In the last 
analysis this expression is used to describe that condition 
of the normal body, plant or animal, in which it is able to 
cope more or less successfully with unfavorable influences 
acting upon it from without, i.e. from the environment. 
There is, however, no quantitative measure of vital resist- 
ance ; but when it is regarded as small or altogether 
wanting, the term is no longer used, and the organism is 
said to be not vitally resistant, but "susceptible" or "vul- 
nerable " to disease. At the other extreme, when the vital 
resistance is complete, especially in regard to parasites, 
poisons, etc., the organism is said to be " immune," as are, 
for example, the arsenic eaters of Styria against ordinarily 
lethal doses of arsenic, and as are certain trees to certain 
parasites. Enough has perhaps already been said in the 
previous section in regard to susceptibility of different de- 
grees, but immunity is a matter of so much practical impor- 
tance that it will be necessary to consider it much more 
carefully in the following sections. 



CUMULATIVE EFFECTS OF UNSANITARY FACTORS 75 

It has been suggested by Professor Theobald Smith that 
the mutual relations of vital resistance and infectious dis- 
ease may be the more clearly appreciated by expressing 

M 
them in the form of an equation, namely, D — — , in which 

R 

D represents the disease, M the micro-organism and R 
the vital resistance of the organism attacked. Obviously, 
D will vary according to the relative values of M and R. 
It is even possible to carry this idea somewhat farther and 

to write the equation D = — — — , N representing the num- 

R 

ber of micro-organisms and V their virulence ; for there is 
good reason to suppose that the intensity of the disease de- 
pends on these factors as well as, though less than, on M y 
the specific character of the micro-organism involved. We 
are unable at present to resolve R into any component 
elements or even to picture to ourselves, except in the 
most general way, its origin or mechanics. We may, it is 
true, safely consider that it is bound up with chemical and 
physical processes which result in favorable chemical and 
physical conditions ; but concerning these processes, and to 
a great extent these conditions, we are at present almost 
completely ignorant. (Cf. pp. 98, 218.) 

§ 8. — Immunity 

Examples of comparative immunity to infectious disease 
are familiar in the cases of all robust and healthy persons. 
Precisely what the basis of this immunity may be it would 
be difficult to say, but it is not inconceivable that in an 
organism which is a practically perfect mechanism the con- 
ditions should be such as to ward off effectually all micro- 
organisms, either by mechanical or physiological defences. 
Among the former would be healthy and vigorous skins 
and epithelia, which the invaders should find it impossible 
to penetrate; among the latter, juices of the body of such 
composition as to be essentially toxic or destructive for 



J6 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

invading microbes. There is good reason to believe that 
such conditions are, in fact, some at least of those which 
constitute the robustly healthy organism immune to all 
ordinary infectious diseases. 

It has long been the ambition of dreamers to find some 
substance which should not only ward off the attacks of 
infectious disease but also interfere with the ordinary 
course of Nature, and postpone for a longer or shorter 
time the arrival of old age. Various elixirs of life have 
been put forward by enthusiasts, especially with a view to 
the latter result, and it must be allowed that, improbable 
as it is that this end will ever be achieved, it is not per- 
haps theoretically inconceivable. It is plain, however, that 
inasmuch as there frequently exists already a remarkable 
natural immunity to certain infectious diseases, the problem 
of artificial immunity to disease is one much easier; and 
when we learn, as is the fact, that such immunity has 
actually been produced in the case of some diseases, we 
may confidently expect that it shall be eventually brought 
about in the case of other diseases also. 

§ 9. — Immunity to Small-pox. Inoculation 

The development of our knowledge in this direction is 
interesting and instructive. The first systematic steps 
toward securing artificial immunity from disease appear to 
have been taken in the case of small-pox. In the early 
part of the eighteenth century, Lady Mary Wortley Mon- 
tagu, the wife of the British ambassador at Constantinople, 
the daughter of a duke and the granddaughter of an earl, 
and a woman of rare gifts, in interesting letters sent from 
Constantinople to friends at home pointed out that the 
Turks, in pursuance of a custom apparently derived from 
the East, were in the habit of " inoculating " against small- 
pox. Lady Montagu wrote from Adrianople in 171 7: 
" Every year thousands undergo this operation, and the 



NATURAL VS. ARTIFICIAL IMMUNITY J? 

French ambassador says pleasantly that they take the 
small-pox here by way of diversion, as they take the waters 
in other countries. There is no example of any one hav 
ing died of it, and you may believe I am satisfied of the 
safety of their experiment since I intend to try it on my 
dear little son." Largely as a result of this correspondence 
the practice of inoculation was introduced into England, 
and thence carried to America. In both countries it be- 
came widely extended, and lasted for many years. It is 
said that the first person inoculated in England was Lady 
Montagu's daughter. George I and several members of 
his family were soon after inoculated, as were also many 
less noted persons, and the practice gradually became 
common. 

In the process of inoculation for small-pox, some " mat- 
ter" derived from a pustule of a small-pox patient was 
introduced under the skin of a healthy person who elected 
to suffer from the disease while well, and knowingly, 
rather than to run the risk of " taking" it when less well, 
unknowingly. The process was much the same as that 
employed in vaccination except that the " matter " used was 
derived directly from the pustules of a small-pox patient, 
and was not " vaccine " matter, i.e. was not derived either 
directly or indirectly from the cow. Inoculation had a 
very extended vogue and was justly regarded as a most 
important defence against small-pox ; and until the milder 
method of inoculating "vaccine " matter, i.e. matter derived 
from the cow, was devised by Jenner, no other method of 
prevention of small-pox, or, for that matter, of any infec- 
tious disease, was known or practised. 

The attitude of mankind at various times toward small- 
pox, inoculation and vaccination forms one of the most 
remarkable chapters in the history of the human race. It 
is impossible to-day to realize the dread and awful terror 
with which this horrible and most loathsome disease was 
justly regarded by our ancestors before the introduction of 



78 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

inoculation and vaccination. A single brief quotation may 
help to give the reader some idea of the feeling in regard 
to it and its prevalence, even as late as the middle of the 
eighteenth century. " Small-pox has been for ages, and 
continues to be, the terror and destroyer of a great part of 
mankind. ... In the ordinary course and duration of 
human life scarce one in a thousand escapes the small- 
pox." . . . (Appendix to Dr. Brooke's " General Practice 
of Physic," London, 1766.) It would be easy to multiply 
authoritative statements of the fearful ravages of this dis- 
ease, and to bring forward testimony to its abundance, 
contagiousness and foul character. Fortunately, it has 
become to-day in civilized countries so uncommon that the 
former dread of it has largely disappeared from the popu- 
lar mind. Unfortunately, however, unfamiliarity with it 
has bred a contempt for it which leads many to despise, 
undervalue or refuse the means by which it is chiefly kept 
in abeyance. Such contempt is likely, if it becomes gen- 
eral, to carry with it its own punishment, for small-pox is 
so contagious that its recrudescence at any time in any 
community is natural and easy, if the very simple means in 
our possession for holding it in check are long neglected. 

The art of inoculation for the prevention of small-pox appears to 
have been long known and to have come to Constantinople from the 
East — from the Circassians in one direction and from the Chinese in 
another. By the Chinese the dried pustules are said to have been kept 
in bottles, inoculation being produced, when desired, by placing por- 
tions of these pustules in the nose of the patient. 

The results of inoculation appear to have been remarkably success- 
ful and under favorable circumstances to have approached, though they 
did not equal, those attained by vaccination. Sir George Baker, a dis- 
tinguished authority, writing in 1766, affirms, "According to the best 
information which I can procure, about seventeen thousand have been 
thus inoculated, of which number no more than five or six have died." 
Another writer of the same time says, "Scarce one in one hundred 
miscarries, whereas a fifth or a sixth part die of the natural small-pox." 
Dr. Hadow, of Warwick, is said to have practised inoculation for 
twenty-seven years, and out of 2143 persons inoculated only three 



« INOCULATION " AGAINST SMALL-POX 79 

(children) died : of these one of an overdose of opium, one in very hot 
weather, the third of nose bleed. 

Much importance was attached by the best practitioners to "pre- 
paratory treatment " of various kinds, although in the East this was 
less regarded. Sir George Baker quotes Gatti, " who some time ago 
was much employed in inoculation at Paris" as "an enemy to any 
general plan of preparation. In all the Levant, he says, where the 
natural small-pox is as fatal as elsewhere, and where you may find 
old women who have inoculated ten thousand people without an 
accident, the only inquiry is, whether or no a person is prepared by 
Nature. All that is considered is whether the breath be sweet, the 
skin soft, and whether a little wound in it heals easily. Whenever 
these conditions are found, they inoculate without the least apprehension 
of danger." ("An Inquiry into the Merits of a Method of Inoculating 
the Small-pox," etc., London, 1766.) In America, where inoculation 
was also much practised before the introduction of vaccination, prepar- 
atory treatment was common, and Sir George Baker (/. c.) states on the 
authority of Dr. Huxham that " Dr. Benjamin Gale, of Connecticut, in 
New England, since he has given mercury and antimony in preparing 
persons for inoculation, has lost only one person out of eight hundred 
inoculated." (On inoculation in New England, see Dr. Zabdiel Boylston 
"An Historical Account," etc., Boston, 1730; in Massachusetts, see J. 
M. Toner, in Mass. Med. Soc. Trans., Vol. II, p. 151, Boston, 1867 ; in 
Great Britain, see W. Woodville, "Hist. Inoc. Small-pox," etc., London, 
1796.) For Dr. Gale's paper see Phil. Trans. Roy. Soc, London, 1765. 

The drawback to inoculation was that persons inoculated had for the 
time being mild cases of genuine small-pox, and were therefore capa- 
ble of conveying the disease to others. They became, temporarily 
at least, " foci of infection," and were usually treated as such, being 
often gathered together in inoculation " hospitals " or establishments 
in relatively remote and inaccessible places, and kept meanwhile under 
more or less strict quarantine regulations. Those who voluntarily re- 
sorted thither for inoculation naturally went, or were sent, while in good 
health or well " prepared," and, for the time being, were completely 
separated from their families. It was a successful, but rather dangerous 
and troublesome method of combating the disease, and when vaccina- 
tion, equally and perhaps more protective and neither difficult nor 
dangerous, was introduced (in 1796), inoculation fell into disrepute and 
was finally forbidden by law (in 1840, in England). Like its successor 
and superior, inoculation of cow-pox (vaccination), the practice of 
inoculation of small-pox met with strenuous contemporary opposition, 
but the esteem in which it was held by the most eminent physicians 
and scientific men of the time is sufficient evidence of its value. " It 



80 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

cannot be, likewise it ought not to be, concealed that some of the 
inoculated have died under this process even under the care of very 
able and experienced practitioners. But this number is so small that 
when compared with the mortality attending the natural smallpox it 
is reduced almost to a cypher." (Dimsdale, " The Present Method 
of Inoculating for the Smallpox," etc., London, 1767). 

Inoculation for small-pox will always remain for the 
student of hygiene one of the most interesting episodes in 
the development of sanitary science, 1 for it illustrates in the 
clearest manner some of the fundamental phenomena of 
infection, susceptibility, vital resistance and immunity — 
and these are among the principal problems of hygiology. 

§ 10. — Vaccination 

Vaccination (Vacca, cow) is simply a modification of 
inoculation in which "matter " of cow-pox taken originally 
from the cow is substituted for " matter " of small-pox 
taken from man. It is immaterial for our present purpose 
whether cow-pox is or is not small-pox in the cow. The 
important fact is that inoculation of the matter of cow-pox 
into the body of human subjects is believed by those most 
competent to pronounce an opinion to prevent or weaken 
the virulence of small-pox in such subjects. Experts are 
unanimous in this opinion, and the methods and results of 
vaccination — the immortal discovery of Jenner in 1796 — 
are too familiar to require comment. By its universal 
application small-pox, as experience shows, can be not 
only held in check but virtually exterminated. 

In its infancy vaccination, like inoculation, had to en- 
counter strong opposition based upon ignorance and a 
natural dread. " Discoveries in physic, as in every other 

1 Jonathan Edwards, the famous New England theologian, was installed as 
President of Princeton College on February 16, 1758, when small-pox was 
prevailing in the neighborhood. As an act of precaution he was inoculated, 
although after some hesitation and while he was in poor physical condition, 
and died thirty-four days after his inauguration. 



" VACCINATION " AGAINST SMALL-POX 8 1 

science, are in their infancy liable to censure and opposi- 
tion ; and as the present system of inoculation is of so 
extraordinary a kind, it would not be strange if a greater 
portion of both than usual should fall to its share." 
(Dimsdale, /. c, 1767.) The remarkable fact is that long 
after its success has been abundantly demonstrated, and 
after its period of " infancy " may be regarded as having 
been long since passed, the practice of vaccination should 
still be not only rejected but also violently attacked by some 
persons of intelligence. The fundamental reason for this 
paradoxical state of things is, doubtless, that assigned above 
by Baron Dimsdale, namely, the "extraordinary " character 
of a treatment which consists in " inoculation " of any kind. 
Persons who of their own motion or on the advice of their 
physicians will cheerfully and even eagerly swallow " medi- 
cines," often of a poisonous character, the very names of 
which are unknown to them, will sometimes refuse to obey 
their medical advisers when these recommend vaccination, 
— the former custom being " ordinary " and hoary with age, 
the latter still comparatively novel and " extraordinary." 

The precise mechanism of that immunity which is the 
most remarkable and most valuable sequel of inoculation 
(or vaccination) is still a mystery. Some light, however, 
has been shed upon the problem by the discoveries of 
Pasteur, Metschnikoff and Behring, and their successors, to 
a consideration of which we may now turn. 1 (Cf. p. 318.) 

§ 11. — Pasteur and Attenuation 

While germs or microbes characteristic of small-pox or 
of cow-pox have never yet been satisfactorily isolated, 
analogy compels us for the present to assume their exist- 
ence. A consideration of the corollaries resulting from the 
application of the germ theory to these long-known and 

1 For an excellent short modern treatise, see " Vaccination," by S. M. 
Copeman (Macmillan), 1899. 



82 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

world-famous diseases led Pasteur, in 1877, not indeed to 
a solution of the problem of immunity, but to an important 
extension of the art of vaccination, and new and inter- 
esting examples of the immunity-phenomenon. Pasteur 
reasoned that, if an infectious disease be really a struggle 
for supremacy between man and microbe, it is probable 
that in vaccination for small-pox the struggle is less severe 
for the patient because the germs of small-pox have some- 
how been weakened or enfeebled by their residence in the 
cow. If this hypothesis were correct, he might hope to 
lessen the virulence of any microbe by subjecting it to an 
unfavorable environment or treatment. Heat, cold, dilu- 
tion, starvation, overfeeding, etc., suggest themselves as 
possible agents for weakening virulence; and by experi- 
ment Pasteur actually produced enfeebled or " attenuated " 
cultures of anthrax, chicken cholera, etc., with which he 
was able successfully to " vaccinate " (if the term may still 
be used) various animals, rendering them more or less 
immune to the diseases respectively investigated. In a 
dramatic public demonstration, in 1880, Pasteur proved 
conclusively the practicability of his method, which, since 
that time, has passed into common use in France for the 
vaccination of domestic animals. 1 (Cf. pp. 321-324.) 

As a result of Pasteur's labors, fresh examples of immu- 
nity were provided, and the practicability of its artificial pro- 
duction was strongly emphasized ; but the basis of immunity 
or the physiological mechanics by which it comes to pass 
and persists remained as great a mystery as ever. 

§ 12. — Metschnikoff and Phagocytosis 

A highly ingenious theory of immunity was suggested 
in 1882 by E. Metschnikoff, who, starting with the well- 
known fact that the white blood-cells are eating-cells (or 

1 See "Louis Pasteur: His Life and Labors" (Radot), New York, Apple- 
ton, 1885, pp. 220-246. 



THE STRUGGLE OF MAN WITH MICROBE 83 

phagocytes) and readily devour yeast-cells, bacteria-cells, 
etc., made elaborate and important investigations tending 
to show that, in the struggle between man and microbe 
which may be said to constitute the essence of an infec- 
tious disease, the battle is really between the white blood- 
cells and the microbes, after the latter have somehow 
secured entrance into the body proper, and especially into 
the blood-vessels. Metschnikoffs theory of immunity is 
therefore known as the theory of phagocytosis. It has 
the merits of simplicity and picturesqueness ; but, while 
doubtless containing much that is true, it fails at one of the 
most important points, namely, in explaining the persistence 
of immunity long after the disease is over except indeed 
on the somewhat too anthropomorphic theory that the pha- 
gocytes have become "trained" or "educated." It fails, 
also, to account satisfactorily for some of the remarkable 
phenomena afforded by blood-serum experiments, such as 
those now to be described. 

§13. — Behring and Antitoxic Serums 

In 1892 an entirely new line of experiment was 
opened up by Behring and Kitasato in their work on diph- 
theria. It was discovered by them that the serum of an 
animal which had been made immune to the toxin of diph- 
theria was able, even in a test-tube, to neutralize or impair 
the virulence of such a toxin, and further that the serum 
of a non-immune animal was not able to do this. Clearly, 
then, substances exist in the serum of an immune animal 
which were not there before the process of immunization, 
and our present theory of immunity rests upon this fact. 
The process of immunization according to the serum theory 
may be described as follows : the microbe (or its toxin) 
irritates the cells of its host ; these produce defensive sub- 
stances or antidotes (antitoxins), which tend to neutralize 
the poison, or to inhibit the activity, of the microbe, or both. 



84 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

If we assume victory for the cells, we have temporary im- 
munity or convalescence. Victory for the microbe means 
continued disease or death. If we may assume that the 
cells of the body continue to secrete more or less of the 
defensive substances, or that they remain for a long time 
peculiarly sensitive to even minute doses of the toxin in 
question, we can understand the persistence of more or 
less immunity. But these assumptions, while plausible and 
perhaps reasonable, are purely hypothetical. 

If we assume, as we may if we like, that the phagocytes 
of Metschnikoff are the principal productive sources of 
antitoxic substances, we have a certain harmony between 
the two rival theories which is, to say the least, conceivable. 
Much, however, remains to be done before any theory of 
immunity can be received as more than very imperfectly 
explaining all of the facts. 1 



§ 14. — Serum as Cure and Serum as Prevention 

The practical outcome of Behring's work has been of 
immense importance, especially in the cure and prevention 
of diphtheria. Patients suffering from this disease, and 
persons exposed or likely to be exposed to it, may and do 
have their own antitoxic serum reenforced by the antitoxic 
serum of the horse or other immune animal and thus are 
materially aided in their battle with the microbes. The 
process is simple. Microbes of diphtheria are cultivated 
in a richly nutrient liquid which gradually becomes charged 
with their toxin. The liquid is filtered, and portions of 
the toxin-bearing filtrate are subcutaneously injected into 
horses, beginning with small doses and continuing until the 
animal is immune to large doses. Blood is then drawn 
from the immune horse, and the serum from this blood is 

1 For further remarks on Vital Resistance and Immunity, see Chapter V, 
§ 6, and Chapter XIII. 



REVIEW OF THE ZYMOTOXIC THEORY 85 

found to contain antitoxin in abundance. This serum is 
carefully filtered and then used subcutaneously as a reen- 
forcing remedy for persons actually ill with diphtheria, or 
as a preventive medicine by those who either may be or 
may have been " exposed " to it. The results of the serum 
treatment have everywhere been most significant and 
encouraging. 

§15. — Recapitulation 

This brief statement of our present attitude in respect to 
infectious disease must suffice for the student of sanitary 
science. Those who desire to go further along these lines 
should consult the numerous excellent manuals of bacteri- 
ology, in which they will find a rich store of materials to 
draw upon. It is enough for the student of sanitary 
science to know that infectious diseases are now believed 
never to arise spontaneously or de novo, but only more or 
less directly from antecedent cases of the same disease. 
It is believed that in every instance there must be an 
actual invasion of, or at least contact with, the suscepti- 
ble patient by the micro-organism of the disease in ques- 
tion. Once inside or upon the patient, the micro-organisms 
may grow and multiply, producing at the same time their 
own peculiar toxin or toxins, precisely as yeast, whether in 
wine or beer or other fruit juices, produces alcohol as one 
outcome of its peculiar vital activity. The illness of the 
patient is believed to be due to the effect upon his body of 
these specific poisons, by which he may die, or to which he 
may become habituated. In the latter case he is said to 
be immune, very much as the smoker becomes immune to 
considerable doses of tobacco, or the arsenic eaters of 
Styria to heavy doses of arsenic, or opium eaters to opium. 
The physiological mechanism of immunity is still to a great 
extent a mystery, but one feature of it appears to be a 
cellular reaction to the foreign toxin, accompanied by the 
production of antidotal substances (antitoxins) capable of 



86 THE "STRUGGLE FOR EXISTENCE" AND DISEASE 

neutralizing the microbic poisons (toxins). Whether the 
cells once affected may be said to have become " habitu- 
ated " to the poison, and if so what, precisely, such 
" habituation " means, is less clear, and further investiga- 
tions are required to elucidate this part of the problem. 
Meantime the practical value of the work already done is 
very great, and the antitoxic serum for diphtheria has 
become one of the most important weapons of the physi- 
cian and the sanitarian. 1 

1 The author is indebted to Dr. J. H. McCollom, Instructor in Contagious 
Diseases in Harvard University, and Resident Physician, South Department 
(Contagious Diseases), Boston City Hospital, for the following facts: — 

Before the advent of antitoxin the fatality in cases of diphtheria (in hos- 
pitals) varied from 30 to 50 per cent. In 11,598 cases in the Asylums' Board 
Hospitals, London, without antitoxin, it was 30.3 per cent. In the same 
hospitals, with antitoxin, it has been 18.4 per cent. In the Boston City Hos- 
pital, without antitoxin, the recent fatality was 46 per cent; with antitoxin, 
it has been 12.9 per cent. Bayeux, in his work on diphtheria, gives 55 per 
cent without, and 16 per cent with, antitoxin, the latter figure being based 
on an analysis of more than 200,000 cases. Bayeux adds that not a single 
death has been clearly demonstrated to have been due to the use of the 
serum. 

Other statistics may be found in Quar. Pub. American Statistical Assoc, 
VII, 53 (June, 1901), and in 33d Ann. Rep. State Board of Health of Massa- 
chusetts, for 1900, p. 768. 



PART II 

INFECTION AND CONTAGION: THEIR 
DISSEMINATION AND CONTROL 



CHAPTER V 

ON INFECTION AND CONTAGION : THE PATHS AND PORTALS 
BY WHICH THEY ENTER THE BODY; THE RESISTANCE 
WHICH THE BODY OFFERS J THE VEHICLES BY WHICH 
THEY ARE CONVEYED J AND THE PLACES OF THEIR ORIGIN. 
ANIMALS AND THEIR EXCRETA AS SOURCES AND PRIME 
MOVERS OF INFECTION 

"Fur die Verbreitungsweise der Infectionskrankheiten kommen 
zunachst in Betracht die Infectionsquellen, die Transport wege, welche 
von dort zum Menschen ftihren, und die Invasionsstatten, an welchen 
das Eindringen der Infectionserreger in den gesunden Korper erfolgt. 
Sodann haben wir der individuellen Disposition und der Immunitat 
besondere Beachtung zu schenken, da diese Momente die Verbrei- 
tungsweise mancher Infectionskrankheiten in hohem Grade beeinflus- 
sen." — Flugge. 

" Exact scientific knowledge of the contagia and of their respective 
modes of operation is of supreme importance to the prevention of 
disease. With even such knowledge of them as already exists diseases 
which have in past times been most murderous .... can, if the 
knowledge be duly applied, be kept in subjection." — Simon. 

§ i. — Infection, Infections Substances and Infectious 
Diseases 

In order that apple juice shall be fermented by yeast 
micro-organisms must somehow find access to it. But the 
normal apple is protected from the invasion of yeast both 
by its skin — a mechanical or structural defence — and 
probably also by specific properties of its living cells, which 
properties, though they are not understood, are recognized 
and described by the term "vital resistance." The skin of 
the apple must be broken and vital resistance overcome 

89 






90 ON INFECTION AND CONTAGION 

before yeast can make its way into either juices or tissues, 
successfully " infecting " them and producing those changes 
which we call fermentation. It may even be said that the 
apple is " hermetically sealed " by its skin, for no sound 
apple can be infected or fermented by yeast unless its 
body has been penetrated either by living yeast cells or 
else, what is yet an open question, by soluble and diffusi- 
ble products of yeast. 

The word " infection " (from in and facer e) signifies 
" entrance " or, literally, " making into," and in sanitary 
science it means in the first place, a process, namely, the 
entrance into a living body, whether plant or animal, of 
something capable of producing disease. Contagion, as 
will be explained presently, is only a special kind of infec- 
tion. The words "infection" and " contagion " are also 
used, in the second place, in another sense, substantively, — 
"the infection," " the contagion," — to represent the infec- 
tious or contagious material itself. From what has been 
said in the preceding chapters it is plain that infection of 
the human body is usually its invasion by parasitic micro- 
organisms, each specific invasion constituting a specific 
infection ; and the " infectious diseases " are those which 
are produced by such invasions. The term " communica- 
ble " is also much used for this group of diseases. In 
practice the word "infection," when used for infectious 
materials, is usually applied to living materies morbi capa- 
ble of growth and multiplication in the body of the infected 
plant or animal and of transfer from one victim to another. 
Etymologically speaking, to be sure, it might be applied 
also to inorganic matters such as metallic poisons, — lead, 
copper, arsenic, etc., — or to organic but lifeless poisons, — 
such as the venom of serpents, the vegetable alkaloids, 
etc., — introduced in any way into the living organism ; but 
as these are doubtless also communicable (though rarely 
communicated), either term may be used at will, both being 
clearly inferior in descriptive accuracy to the term "zy- 



DEFINITIONS 91 

motic," which, after all, is probably the most correct and 
comprehensive name for those diseases which are essen- 
tially attacks upon the plant or animal body by living fer- 
ments. That these ferments happen also to be more or 
less readily " communicable " is an incident only and not 
their principal characteristic; and that they are "infectious," 
or capable of entering the body, is a property which they 
share with diseases caused by other environmental agen- 
cies, such as lightning, arsenic and toadstools mistaken for 
mushrooms. 



§ 2. — The Skin and Epithelia as Structural Defences of 
the Living Body against the Invasions of Disease 

As the normal apple is protected by its covering or 
skin, so the normal living body is protected by its cover- 
ings — skin and epithelia — from the invasion of parasitic 
or fermentative micro-organisms or their products. It is 
perhaps too much to say that the living body is hermetically 
sealed, and yet modern physiology teaches that one of the 
principal offices of the skin is protection against forces or 
substances acting from without, and that the cells of the 
more delicate epithelia covering the lung surfaces and the 
alimentary and genito-urinary tracts have as one of their 
specific duties a certain discriminating authority over the 
matters likely to pass through or to be absorbed by them. 
In somewhat more than a metaphorical sense, therefore, 
it may be safe to say that the living animal body is her- 
metically sealed against the invasion of matters proceed- 
ing from the environment. The phrase, once much used, 
which referred to any rupture of this seal as a " solution 
of continuity " undoubtedly referred to the same idea, and 
marks the recognition of the essential integrity of the body 
surfaces as one condition of health. 

In order that any germ, whether parasitic or not, shall 
find entrance into the living body, it must be able some- 



92 ON INFECTION AND CONTAGION 

how to pass through the ordinary defences. In the case 
of the skin it would appear that an actual rupture must 
take place, as happens, for example, in a puncture, incision, 
bruise or other mechanical injury. In the case of the 
epithelia, it may be that a similar passage by force is neces- 
sary, or it may be that the living cells which here line the 
surface externally are, so to speak, off their guard or for 
the time being actually facilitate an invasion which, from 
their delicacy, is here more easily effected. At any rate, 
it is easy to see that for the actual entrance of micro- 
organisms into the body proper an unusual and direct 
passage must somehow be provided. As to the absorp- 
tion of the toxic products of germ life we shall have some- 
thing to say in § 5. 

It should not be forgotten that by " the body proper " 
is meant that portion of it enclosed within the skin and 
epithelia; the cavities of the alimentary canal and the 
genito-urinary tracts not being included, inasmuch as they 
are really portions of the environment merely passing 
through or dipping into the body-mass. 

§ 3. — Infection by Way of the Skin. Invasion by Force 

The processes of infection by way of the alimentary canal 
and the genito-urinary tract, to be described in § 5, are typi- 
cal of a large class of the more obscure infectious diseases. 
There is, however, another and commoner path by which 
micro-organisms obtain entrance into the body proper, and 
that is directly through the skin, the diseases to which they 
give rise being known as "wound" diseases. Many of 
these are familiar, as, for example, the results of simple 
punctures made by small foreign bodies such as pins, 
needles, " slivers " and the like. When these carry in with 
them micro-organisms capable of setting up fermentation 
or inflammation, the infection thus produced may be either 
local or general : in the former case leading to the condi- 



SKIN AND EPITHELIA AS PORTALS OF INFECTION 93 

tions familiar in such unimportant local wounds as those 
mentioned ; in the latter to septicaemia, or dangerous blood 
poisoning, a kind of fermentation of the whole body. Occa- 
sionally it happens that a wound made by a sliver or some 
other ordinarily insignificant object, such as a needle or a 
bee sting, is followed not merely by the usual local inflam- 
mation, but by a far more serious and extensive injury and 
even by speedy death. It is supposed that in these cases 
either the infection was of an unusual and severe type — 
by which is meant that the micro-organisms were unusually 
abundant or of some unusually virulent species — or else 
that the vital resistance of the cells and tissues of the victim 
happened to be poor in kind or at a low ebb, so that even 
ordinary micro-organisms met with specially favorable 
conditions. In a word, either the infection was unusually 
powerful or the patient was unusually susceptible. It is, 
of course, possible to conceive of a third condition resulting 
from an unfortunate coincidence or combination of the 
other two. 

§ 4. — Wounds and the Diseases of Wounds 

The punctures and other simple infections by way of 
the skin just described belong in the same class with 
more serious interruptions of continuity such as gun-shot 
wounds, compound fractures, abrasions and the like, among 
which must be classified as of the highest practical im- 
portance surgical operations such as excisions of tumors, 
amputations, the tying of arteries, etc. In these cases the 
bullet, the surgeon's or dissector's knife, or other foreign 
body of relatively large size, may readily be a vehicle for 
the germs of infectious disease. It has already been 
pointed out how the classical inductions of Lister and his 
application of the germ theory and its corollaries to this 
class of diseases has led to results of the first importance 
in this direction, namely, to sanitary or aseptic surgery. 
(See p. 45.) 



94 ON INFECTION AND CONTAGION 

There is one disease of wounds particularly interesting, 
for various reasons, to the sanitarian as well as to the sur- 
geon, namely, tetanus or " lock-jaw." It had long been 
known from observation and experience that certain punc- 
tures or incisions, especially those made by the entrance or 
laceration effected by dirty foreign bodies, were not infre- 
quently followed by a peculiar condition of the patient in 
which tetanic muscular spasms were a prominent feature, 
when, in 1884, Neisser isolated from garden soil a bacillus 
capable on inoculation into mice and rabbits of producing 
a similar disease. Further investigations have confirmed 
the discovery, and the natural history of the Bacillus tetani 
is now well known. It is frequently found in the earth 
and it is widely distributed in nature. It is anaerobic, i.e., 
it thrives best in the complete absence of oxygen. Culti- 
vated in bouillon, it produces a powerful poison (toxin) 
which appears to realize the early speculations of Dr. Farr, 1 
and which, even in the absence of all living bacteria, is 
capable of producing typical tetanic convulsions. A sub- 
stance apparently identical with it has been separated from 
the muscles of patients dead of tetanus, and this substance, 
when injected into the lower animals, produces in them 
tetanic spasms. It may be added that an antitoxin capa- 
ble of neutralizing the toxin of tetanus has more recently 
also been prepared and used. 

i The importance of the bites and stings or other punc- 
tures of the skin by insects, which has long been recog- 
nized theoretically, has recently received fresh emphasis 
and attention, owing to the results of investigations upon the 
hitherto obscure but widespread disease known as malaria. 
It is now believed that the female of a species of mosquito 
is the principal vehicle of this disease ; that the mosquito 
becomes itself inoculated by drawing the blood of malarial 
human subjects in whom the germ of malaria exists, often 
in the red blood-cells ; that in the mosquito the malarial 

1 " Vital Statistics," I.e., pp. 244-245. 



MOSQUITOES, MALARIA, YELLOW FEVER 95 

germ develops ; and that by the mosquito it is injected 
with the saliva as an inoculation into fresh victims during 
the bite or sucking of the animal. Dog-bite and accom- 
panying hydrophobic inoculations also plainly belong in 
this class of wound diseases. 

The researches of Laveran, Manson, Ross, Celli and 
others upon malaria, and mosquitoes as hosts of the malaria 
parasite, form one of the most brilliant and instructive 
chapters in the history of sanitary science and experi- 
mental medicine. The parasite, which infects the red 
blood-corpuscles of its victim, had been recognized for 
several years, but nothing whatever was known of its life 
outside the animal body or the method of its distribution 
until it was discovered that the female of at least one 
species of mosquito {Anopheles) is capable of acting as an 
effective vehicle of the micro-parasites (haematozoa). 

Further discoveries have shown that the Anopheles must 
itself become inoculated by sucking the blood of a malarial 
animal; that the parasites undergo an important part of 
their development within the body of the mosquito (which 
is therefore a host as well as a vehicle of the microbes) ; 
and that they are conveyed to animals bitten by the mos- 
quito with the salivary poison injected during the bite. 
The mosquito, in short, is an intermediary host, precisely 
as is the hog in the life-cycle of Tcenia, the pork tape- 
worm. The practical importance of these discoveries is 
immense, for it has already been established by experi- 
ment that man may live in " malarious " districts with no 
risk of contracting malaria provided pains are taken to 
avoid absolutely all mosquito-bites ; and on the other hand, 
it has been shown that mosquitoes that have bitten mala- 
rial subjects may readily transmit the disease by their bites, 
and infect fresh victims even in regions hitherto abso- 
lutely free from malaria. 

More recently still evidence seemingly conclusive has 
been obtained — at great personal risk, and with admirable 



96 ON INFECTION AND CONTAGION 

courage — by American investigators in Cuba that yellow- 
fever is similarly transmissible by mosquitoes, and not 
readily, if at all, by infected bedding or other lifeless 
materials. 

Flies have of recent years come to be regarded as ready 
vehicles of infection, and especially of typhoid fever. 
Lime scattered over excrements in privies has been ob- 
served on the feet and legs of flies running over food set 
out for eating upon tables in the neighborhood, and if 
lime can be thus carried, there is no reason why microbes 
also may not be carried to food or drink. It is also prob- 
able that the bites of flies may convey infection, although 
this has not yet been established. It is believed, however, 
by experts that one of the principal sources of typhoid 
fever in army camps is the infection of food by flies acting 
as vehicles of the microbic infection. 

Those who would pursue these subjects further are re- 
ferred to the following works : Celli, " Malaria according 
to the New Researches " (English translation by Eyre and 
an Introduction by Dr. Patrick Manson), Longmans, Green 
& Co., 1900; Howard, L. O. " Mosquitoes : How they Live, 
How they carry Disease," etc., New York (McClure), 1901. 

§ 5. — Infection by Way of the Alimentary Canal, Lungs 
and the Genito-urinary Tracts 

The alimentary canal being in free connection with the 
environment and really a portion of it, is naturally subject 
to invasion from various sources by various micro-organ- 
isms and similar extraneous matters ; and the same thing is 
true of lungs and genito-urinary tracts, though perhaps in 
less degree. The alimentary canal, moreover, is ordinarily 
well stocked with food materials for micro-organisms ; and 
although the gastric juice probably exerts an unfavorable 
influence upon them, it may be said that, on the whole, the 
warm and well-fed alimentary canal affords an excellent 



INFECTION IN DIPHTHERIA AND CHOLERA 97 

breeding-ground for certain bacteria. But if bacteria mul- 
tiply enormously in the alimentary canal, they do so at the 
expense of materials found therein, and in the course of 
their multiplication must produce various substances of the 
nature either of by-products or excreta ; and some of these 
may conceivably be harmful either to the guardian epithelia 
lining the alimentary canal or to the tissues in general, if 
once they are absorbed and distributed by the circulation. 
Similarly, micro-organisms grow freely within the genital 
tracts, and feeding upon the exudations or secretions there 
found may multiply enormously, with the consequent pro- 
duction of deleterious substances which shall damage 
either the lining epithelia or, when absorbed, other tissues 
of the body, near or remote. Moreover, in both these 
cases the paralysis or destruction of the guardian epithelia 
may produce actual solution of continuity, which shall 
allow either the micro-organisms in question or their poi- 
sonous products to find ready entrance into the body 
proper. 

There is reason to believe that the bacillus of diphtheria, 
for example, works precisely in this way. Finding lodg- 
ment upon the tissues of the throat, it proceeds to grow and 
multiply upon the normal exudations and the food materials 
there present, and in the course of its vital activity pro- 
duces somehow some of that poisonous substance which is 
now well known as the "toxin" of diphtheria. This first 
paralyses or otherwise interferes with the normal activity of 
the cells lining the throat in its immediate vicinity, where- 
upon, these cells failing to do their duty, an abnormal exu- 
dation of lymph takes place, and this, coagulating, produces 
the well-known " white patches " so common in " the diph- 
theritic throat." At the same time a powerful poison, the 
toxin, is being absorbed into the general circulation, and 
causes those general or constitutional symptoms which are 
characteristic of the disease. 

In the case of Asiatic cholera, there appears to be first 



98 ON INFECTION AND CONTAGION 

an invasion and then a genuine and extensive fermentation 
of the contents of the alimentary canal, with an enormous 
multiplication of the micro-organisms concerned, so that 
these can readily be detected in large numbers in the 
bowel discharges. At the same time the characteristic 
poison or toxin of Asiatic cholera is supposed to be liber- 
ated, and its absorption through the walls of the alimentary 
canal is supposed to give rise to constitutional symptoms 
characteristic of the disease and indicative of profound 
disturbance of the body proper, such as vomiting, fever, 
sweating and delirium. In these cases, as will be observed, 
it is not the germs themselves, at least in the first place, 
which penetrate into and ferment the body itself. It is 
rather by attacking the frontier, there and then setting up 
their own peculiar fermentations, and producing poisons 
which are easily absorbed, that these micro-organisms 
first do their harm and open the way for themselves or 
other germs to enter into the body proper. Nevertheless 
the process, even from the very start, is one of fermenta- 
tion, directly affecting either the body wall or materials, 
such as partially digested food or secretions, closely con- 
nected with and for the time being practically a part of it. 
(Cf. § 3, P- 92.) 

§ 6. — The Physiological Defences of the Living Body, 
Vital Resistance and Susceptibility once more 

The term " vital resistance " has been much used in the last 
few sections, coupled with the statement that its exact sig- 
nificance is unknown. It is unnecessary to argue again at 
this point that there is such a thing as vital resistance, or 
that it varies largely from time to time. The experience 
and observation of everyday life abundantly testify to these 
facts. Who has not witnessed, for example, that robust 
and abounding health which enables some persons to live 
happily and carelessly in poverty, filth, and squalor, while 



INFECTION THROUGH TOXIN-ABSORPTION 99 

others, surrounded by every comfort and protection, perish 
on the least provocation ? Again, who has not, even in 
himself, known times when almost anything might be done 
with impunity, and other times when the least exposure or 
other unfavorable condition led to indisposition or illness ? 
Who has not remarked over and over again the immu- 
nity of youth, the fragility of age ? In no other way than 
by recognizing differences in resistance to unfavorable 
environments can these anomalies be explained, and the 
term " vital resistance " well sums up and describes facts 
established by the long and accumulated experience of the 
race. It describes the facts, but, as so often happens with 
terms applied to human experience, it does not explain 
them. Sanitary science, however, gladly accepting and 
using the terms "vital resistance " and " susceptibility," — 
the latter being the converse of the former, — seeks to go 
further and learn, if possible, the causes of these condi- 
tions, and the processes by which they are reached. It 
must be frankly admitted that thus far the search has not 
been wholly successful, and yet something has certainly 
been done, at least toward making things clearer and more 
comprehensible. (Cf. pp. 74-85.) 

It is easy to see that " vital resistance " must be largely 
constitutional. It must depend either upon the materials 
of which the body is built or on the way in which these 
are put together, or, more likely, upon both. In order to 
resist the attacks of micro-organisms upon epithelial sur- 
faces ; or to overcome them on their arrival if thrust in by 
force through the skin, as happens in wounds ; or in order 
to neutralize their poisons (toxins) if these succeed in break- 
ing down and passing through the epithelia or the skin, 
mechanical and chemical defences within the body — phys- 
iological defences — would seem to be most useful ; and 
it is therefore interesting to find, as we do, that the modern 
theories of "vital resistance" (which in its most perfect 
form is now called " immunity") proceed along these lines. 

LoFC. 



IOO ON INFECTION AND CONTAGION 

A little reflection will show that micro-organisms on 
entering the body or any of its passages are immediately 
subjected to a peculiar environment, which for many 
species must be highly unfavorable. This may be said to 
be the simplest of the physiological defences. The first 
of these met with may be the gastric juice, which for many 
microbes is highly unfavorable on account of its acidity. 
The comparative immunity of plants to bacterial diseases 
and their relative susceptibility to the attacks of fungi has 
been accounted for in part on the ground of the greater 
acidity of their juices. Those microbes known as " disease 
germs," on the other hand, must be supposed to find the 
new conditions more or less favorable ; more if the patient 
is susceptible ; less if he is endowed with considerable vital 
resistance ; wholly unfavorable only if he is immune. 

Even milk, which is well known for its blandness and 
as a favorable culture medium for many bacteria, being 
literally crowded with certain species when it is stale, has 
been described as " germicidal," 2 so that the first and very 
likely the most important physiological defence of the liv- 
ing body may be the fact that merely as such it furnishes 
an unfavorable environment for many invading organisms. 
The bodies of micro-organisms perishing in the invaded 
territory, whether this be local or general, in the healthy 
animal soon disappear, and there is reason to believe that 
they are removed by the white corpuscles of the blood and 
the lymphatics, acting as scavengers. Whether these de- 
vouring cells (phagocytes) are soldiers as well as scaven- 
gers, whether or not they can kill as well as devour invading 
micro-organisms, is not wholly clear. The view that they 
can and do, and that acquired immunity depends largely 
on their training so that they shall do it successfully 
(Metschnikoff s theory of immunity by " phagocytosis "), 
while it has developed many interesting facts (as stated 

1 " Ueber die Bakterienvernichtenden Eigenschaften der Milch," Baum- 
garten's Jahresbericht ueber Mikroorganismen, VI. 513, 529. 



INTERNAL DEFENCES AGAINST INFECTION IOI 

above), seems somewhat too picturesque and too an- 
thropomorphic. It is not much easier to understand 
with Behring and Roux how the cells of the tissues or the 
blood after one attack of an infectious disease, such as 
diphtheria, are so " affected" that they secrete regularly 
thereafter and in its absence a chemical antidote for the 
diphtheria toxin. 

Perhaps the truth is to be found in a combination of 
these various views. The physiological defences may very 
likely consist in (i) the fact that the living body merely as 
it stands offers to many micro-organisms an unfavorable en- 
vironment for their normal development ; (2) the fact that 
some microbes on entering are seized and devoured by 
phagocytes drawn to them by chemiotactic influences ; 
(3) the fact that over and above the general unfavorable- 
ness of environment, immune animals possess somehow, 
either naturally or acquired, the faculty of subjecting 
special invaders or their products (toxins) to the action 
of special chemical substances (antitoxins) which destroy 
their efficiency. 

It will be observed that in all these cases the defence 
consists essentially in a kind of internal or physiological 
disinfection, which whether real or not is conceivable 
enough. But besides this we have to recognize the fact 
that the living cells of the epithelia appear to have a certain 
power of " selection," at present not understood, Doubtless 
this is no more mysterious than, for example, that power 
of selection which the absorbents appear to exercise, or 
that property of the cells of the stomach or intestine by 
virtue of which they are not digested by their own juices 
respectively. The fact, however, remains at present essen- 
tially unexplained. 

§ 7. — The Precise Meaning of Contagion 

The terms " infection " and " contagion " as applied to 
processes rather than substances (for in the latter case 



102 ON INFECTION AND CONTAGION 

they mean exactly the same thing) may now be further 
denned and explained. The former, strictly speaking, 
signifies " entrance," the latter "contact." Though often 
used as if synonymous, they are not best so used. Infection 
is the broader and larger term, and includes contagion. It 
signifies simply the entrance or " making into " the body of 
harmful material. This may be either living or lifeless, 
but the term is generally applied to the entrance or mak- 
ing in of living organisms by any method or avenue what- 
soever. Contagion, on the other hand, is only a particular 
kind of infection of living organisms or microbes in which 
the infecting substance is transferred from source to sub- 
ject by direct contact, as, for example, when the contagion 
or infection of small-pox is derived by the victim directly 
from contact with a preceding case. Infection is well 
illustrated by cases of typhoid fever or Asiatic cholera in 
which the bowel discharges of a person, A, find access to 
water or milk and are consumed with food or drink by 
another person, B. In this case B may never have seen, 
or heard of, or been anywhere near, A, and there may have 
been no contact whatever between them. In a word, con- 
tagion is direct, immediate — and generally personal — 
infection, while other forms of infection are more or less 
roundabout and indirect. Contagion operates, neverthe- 
less, in precisely the same way as infection. In all cases 
whether of infection or contagion there must be somehow 
a transfer of infectious material more or less directly from 
an antecedent or primary case as a cause, to a consequent 
or secondary case as an effect ; and it matters not, except 
as to details, whether the infectious material is derived 
immediately from the antecedent case by actual contact 
with it, or after the lapse of a long time and in obscure 
and roundabout ways. Both phenomena belong in the 
same category, though the more obvious is called "con- 
tagion" and the less obvious "infection." It would be 
better to drop altogether the term " contagion," and to 



INFECTION VS. CONTAGION 103 

apply to all these cases the simple and accurate term 
"infection," 1 which, if we neglect the idea of entrance by 
force, has almost exactly the same significance as " inva- 
sion," and corresponds precisely to the popular term often 
applied to infectious disease, namely, an " attack." 

§ 8. — Man and Other Animals the Principal Primary 
Sources of Infection 

We have now considered somewhat briefly the portals of 
entrance of infectious materials into the body proper, and 
have hinted at some of the vehicles of infection. Before 
dwelling long upon these it will be well to consider the 
original sources of infectious materials in the environment. 
Once we have determined the sources of infections, it will 
be comparatively easy to discover the avenues of communi- 
cation and the vehicles by which they travel. 

It was formerly supposed that the earth and various other 
non-living materials were prolific original sources of infec- 
tious disease, or in other words, that the germs of disease 
not only exist but thrive and multiply in the earth. It was 
thought, for example, and is still held by some, that the 
micro-organism of typhoid fever passes a portion of its life 
and undergoes a necessary portion of its development in the 
soil, especially in filthy soil, and similar ideas were held in 
regard to other infectious diseases. Doubtless the reason 
for this opinion was to be found in the fact that certain 
animal and vegetable parasites had been known for a long 
time to spend one portion of their lives in or upon some 
plant or animal other than, and often lower than, their 
most conspicuous host. This is true of the tapeworm, the 
Trichina, the blight of barberries, and many other para- 

1 Much confusion in the use of these and related terms exists in the works 
of the earlier authors. Even Dr. Farr (I.e.) refers to " diseases propagated 
either by inoculation and contact (contagion) or by inhalation (infection)," 
and says " miasms produce diseases like ague, without being propagated by 
contagion." 



104 0N INFECTION AND CONTAGION 

sites. The progress of inquiry, however, has not confirmed 
these ideas, except in special cases (such as that of tetanus, 
p. 94), for the ordinary infectious diseases. It has been 
said that some still hold to the idea in the case of typhoid 
fever; but the author believes, after a very considerable 
investigation of the question, and personal studies of epi- 
demics which he has had somewhat unusual opportuni- 
ties to witness, that this idea is not sound, and that every 
case of typhoid fever, at least in the latitude of New 
England, arises rather directly from an antecedent case, 
and in this way only. It is, of course, possible that in 
other latitudes, and under conditions particularly favora- 
ble, the typhoid bacillus may grow outside the human 
body. There is no question that under favorable condi- 
tions it can do this in laboratories ; but that it does so in 
nature in temperate climates, except under very unusual 
circumstances, does not seem to be indicated by the evi- 
dence at hand. It can unquestionably live for some time 
in nature, though apparently with diminishing virulence, 
and in diminishing numbers ; but in northern latitudes 
and under ordinary conditions its prolonged survival, and 
especially its multiplication outside the body, must be 
doubted. 

A similar statement may be made in the case of many 
infectious diseases, and we may safely say that for the 
most part man and other animals are the original sources 
of infectious disease. But it should always be remem- 
bered that under tropical conditions, if only suitable food 
and moisture be present and other conditions favorable, 
the germs of infectious disease may live long and actually 
multiply outside the animal body. 

Since the above paragraphs were written the amazing 
revelations of the role played by mosquitoes in the convey- 
ance and the development of malaria have been made. 
From these it appears that here also a disease long associ- 
ated with swamps and mysterious " miasms " has its sources 



SOURCES AND PRIME-MOVERS OF INFECTION 105 

only in animal bodies, for the malarial parasite comes from 
the bodies of men and mosquitoes, which thus appear to 
be the only original sources of infection. 

§ 9. — Man and Other Animals, and especially their Ex- 
creta, the Principal Primary Vehicles or Prime-movers 
of Infection 

If it be true that man and other animals are the principal 
original sources of infection, it must follow as a matter of 
course that their excreta are its principal original vehicles ; 
for the excreta represent the output of the organism, its 
contribution to the environment. Physiology teaches that 
the material output of the animal body consists of dis- 
charges from the alimentary and genito-urinary passages 
and from the skin, — the nose and lungs being regarded 
as branches of the alimentary apparatus, — and accord- 
ingly it is these discharges which must be the principal 
original vehicles of infectious disease from its place of 
origin to the environment. Diseases have, in the past, 
often been roughly classified according to their place 
of origin and the vehicles by which they are con- 
veyed. An important class of infectious maladies known 
as " diarrhceal " diseases is directly attributed to infections 
from the bowel discharges. Typhoid fever, Asiatic cholera, 
dysentery, diarrhoea, and cholera infantum are the most 
important members of this class. Of equal or even greater 
importance are those diseases known as " eruptive" dis- 
eases, which are readily scattered from seedings of the shed- 
off skin. In these cases, pustules form on the skin and, 
opening to the exterior, discharge their secretions there. 
To this class belong some of the worst diseases that afflict 
the human race, such as small-pox, typhus fever, scarlet 
fever, measles, chicken-pox and many more. Since the 
infectious material is in this case poured out upon the sur- 
face of the body, it is readily transferred by direct contact 
to the fingers, and thereby to the mouths or, when dried, 



106 ON INFECTION AND CONTAGION 

by the wind, to the noses and lungs of other persons. 
Hence, the term " contagious " diseases, especially applied 
to this group. Again, a certain number of diseases 
affecting the mouth, throat, or lungs may be conveyed by 
means of the sputum or saliva thrown out of the mouth 
and eventually finding its way either when dried, pulver- 
ized and blown about by the wind, or through the agency 
of food contaminations, to other susceptible persons. In 
this group would naturally be found diphtheria and pul- 
monary tuberculosis. 

The other excreta, such as the urine and the breath, as 
well as the sweat, are not usually charged to the same 
extent with the carriage of disease. The expired air from 
the lungs, formerly so much dreaded by those who 
watched at the bedside, appears according to the careful 
investigations of bacteriologists to be the least dangerous 
of all the excreta, being practically germ-free. The rea- 
son for this is that the moist, spongy lungs act as an effi- 
cient filter, and not only refuse to yield up micro-organisms 
to the expired air, but even detain organisms arriving in 
the inspired air, so that the outgoing breath of a patient is 
from the bacteriological point of view actually purer than 
the inspired air. Recent researches, on the other hand, 
have shown that the urine may be a ready vehicle of the 
microbes of typhoid, and very likely of other, fevers. 

It is interesting to note, also, that the malarial parasite 
passes from mosquito to man with an excretion, the saliva. 
From man to mosquito it does not pass in this way, but 
rather as a contamination of stolen food, the sucked blood 
being itself infected. 

§ 10. — Earthy Air, Water and Animals the Principal 
Secondary Vehicles of Infectious Disease 

But if the excreta are the principal original vehicles of 
infection, they are by no means the only vehicles, for they 



107 

may readily mingle with and transfer their burden of in- 
fection to almost any substance in the environment. 
From the skin the surrounding air may first become 
infected and then move on, laden with disease, so that 
disease — or rather its germs — may literally be borne on 
"the wings of the wind." Likewise, sputum from the 
mouth, or discharges from the bowels, may be impercepti- 
bly mingled with a stream, so that a cup of cold water — 
the time-honored symbol of purity and charity — may con- 
tain unseen and unsuspected the germs of deadly or dis- 
gusting diseases. Or, again, the earth impregnated with 
human excreta may be dried and pulverized, and, as dust 
infecting human throats, become the vehicle of diseases 
such as diphtheria or tuberculosis. Clearly, if animal life 
is the principal source of infection, and the excreta of ani- 
mals are its principal vehicles, these, being some solid, 
some liquid and some gaseous, are only too likely to find 
kindred substances in the environment with which they 
can mingle, and to which they can convey a portion at 
least of their burden of infection. 

We have already seen how insects may become the 
bearers of infection, and we may now turn, in the follow- 
ing chapters, to a detailed consideration of several other of 
the most important and most common vehicles of infec- 
tion, namely, dirt, dust, air, sewage, water, ice, milk, raw 
foods (such as oysters and salads) and the like, and the 
ways in which these can be protected or purified. 



CHAPTER VI 

ON DIRT AND DISEASE. THE LIVING EARTH. DIRT, DUST 
AND AIR AS VEHICLES OF INFECTION. FILTH, FILTH DIS- 
EASES AND THE PHILOSOPHY OF CLEANNESS 

" Uncleanness must ... be reckoned as the deadliest of our present 
removable causes of disease." — Sir John Simon. 

" Cleanliness covers the whole field of sanitary labor. It is the be- 
ginning and the end." — Dr. B. W. Richardson. 

The experience of the race has shown that one of the 
most effective vehicles of disease is dirt. The word " dirt " 
appears to be derived from an old Saxon word drit, mean- 
ing excrement ; but the modern form of the word " dirt " has 
taken on a more extended and less definite meaning. As 
ordinarily used it may be the synonym of dust, soil, filth 
or almost any form of uncleanness, whether such unclean- 
ness imply the presence of infection or only that of pollu- 
tion. Still it can hardly be denied that even at present 
the word "dirt" signifies something distinctly more filthy 
than do the words " earth," " soil " or " dust." It is easy to 
see in the origin of the word the reason for this, and after 
what has been said in the preceding chapters concerning 
the primary sources of infection and the efficiency of ex- 
crement as a vehicle, no surprise need be felt that dirt 
is regarded with suspicion by all intelligent and well- 
informed persons. 

§ i . — Clean Earth and Infectious Dirt 

Unquestionably the general fear of dirt among the in- 
telligent is not in all cases discriminating. There may be, 

108 



DEFINITIONS IO9 

and probably are, forms of dirt which carry with them 
very little of danger, and a certain recognition of this fact 
is shown in such expressions as " good clean earth." It 
appears to be true that while it is the earth that is most 
often associated with the idea of dirt, it is ordinarily only 
the surface of the earth which is thus looked upon with 
suspicion and aversion. One reason for this probably is 
that the surface or loamy layers of the soil are not infre- 
quently sticky and suggestive of organic matters, while 
the subsoil directly below the loam layer is generally more 
obviously mineral in its character and often clean, i.e. not 
sticky or " dirty." As a matter of fact the loamy layer so 
called is, in truth, richer in organic matters, and besides 
often containing innumerable earthworms is crowded with 
the bodies of micro-organisms. The earthworms by their 
ploughing actions, which Darwin has so admirably worked 
out, are constantly turning over the upper layers of the 
earth, carrying from the surface into the lower strata 
organic matters, and from below to the surface the more 
mineral subsoil. It follows, therefore, that not only is the 
surface of the earth contaminated by excrement of various 
kinds that falls upon it, but also, through the agency of 
earthworms, a considerable portion of the earth just below 
the surface, and especially, no doubt, the loamy layer 
already referred to. 

Accordingly, if we desire to define and classify the terms 
already used, we shall say that earth, broadly speaking and 
for the most part, is essentially mineral in character and 
clean in condition because free from any considerable 
amount of organic matter. It is also, therefore, ordinarily 
free from infection — uninfected as well as unpolluted. 
Soil, i.e. the surface layer of the earth, may be clean, 
and may be and ordinarily is fairly free from infectious 
materials, but inasmuch as it is exposed to contamination 
by dirt, i.e. excrement, and is being continually worked 
over by earthworms, it may be and usually is more or less 



110 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

polluted or contaminated with organic matter. It may or 
may not be infected. Dirt in the original and most exact 
sense is simply excrement, but in the more ordinary use of 
the word is soil, i.e. the surface layer of the earth, which 
may or may not contain infectious materials. 

§ 2. — The Living Earth 

It is one of the most marvellous revelations of bacteri- 
ology that the earth, long regarded as the type of lifeless- 
ness, is in fact, at least in its uppermost layers, teeming with 
life. Not only do many mammals, birds, reptiles, insects, 
and worms have their homes in the earth, but, as bacteri- 
ology teaches, also vast hosts of micro-organisms, more 
abundant by far than the grains of sand upon which they 
dwell. A single gram of garden soil may contain millions 
of micro-organisms, and much of the softness and sticki- 
ness of moist loam is probably due to the presence of such 
numbers of soft protoplasmic bodies. Thus it has come 
to pass that we are no longer at liberty to speak or think 
of the earth, at least in its upper layers, as dead and 
essentially mineral, but must regard it instead as highly 
organic and quivering with life. 

§ 3. — Earth as a Vehicle of Disease. Tetanus or Lockjaw 

once More 

The earth is not only rich in germs, but may contain 
among these some that are pathogenic or disease-produc- 
ing. Reference has already been made to tetanus as 
caused by specific microbes found in the soil (pp. 94, 104), 
and these are especially interesting, inasmuch as they 
appear to lead regularly a saprophytic rather than a para- 
sitic life. In this respect we have reason to suppose that 
they (and a few others) differ from most pathogenic 
microbes, which fortunately do not, under ordinary con- 



THE LIVING EARTH m 

ditions, appear to thrive (though they may continue to live 
for a long time) outside the plant or animal body. 

§ 4. — Dust and Disease 

Dust is pulverized soil or pulverized dirt, and only rarely 
pulverized and pure earth. It is therefore, as a rule, rich 
in bacteria, and may or may not contain infectious disease 
germs. Inasmuch as it is the surface of the earth which 
is ordinarily dried, pulverized and lifted into the air, it is 
easy to see that excrement of any kind, deposited upon the 
soil, sputum and other organic matters cast off by ani- 
mal bodies, — such as scales from the skin, bits of hair, 
dandruff and the like, — as well as the possible combina- 
tion of all these things with dirty water to make sewage, 
may when dried on the surface of the earth be also readily 
pulverized and lifted into the air as fine particles or motes 
of dust. At first sight, dust of this character might be 
supposed to be necessarily dangerous and even deadly, 
and there is very little doubt that infectious diseases are 
in fact frequently transmitted by dust which serves as a 
vehicle; but, on the other hand, it should not be for- 
gotten that there are certain compensating circumstances 
which tend to diminish the dangers of disease from this 
source. The unfavorable conditions to which micro-organ- 
isms are exposed in dust, namely, desiccation, possible ger- 
micidal action of light, unfavorable temperatures and the 
like, undoubtedly destroy many of them and weaken oth- 
ers, but, in spite of these various fortunate conditions, it 
still remains true that dust must always be regarded by 
the sanitarian as dangerous, not only because of the 
mechanical irritation of the delicate mucous membranes 
of the throat and other respiratory passages caused by the 
inorganic particles of which it is largely composed, but 
also because of the possibility of its containing virulent 
disease germs, such as those of tuberculosis or diphtheria 






112 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

from the sputum of persons affected with these maladies ; 
as well as those of small-pox, scarlet fever, measles and 
the like, from the skin-scales of victims of these diseases ; 
and, to a less extent perhaps, the germs of typhoid fever 
and other diarrhceal diseases from the pulverized excreta 
of walking cases, or from night soil spread upon fields for 
manure and afterward dried and lifted into the air by 
winds during the operations of hoeing, harrowing, plough- 
ing and the like. 1 



§5. — The Atmosphere as a Vehicle of Disease ; Ancient 
and Modern Theories 

From the earliest times the atmosphere has been regarded 
with suspicion as a vehicle of disease. Miasms, pestilential 
vapors and various mysterious and unseen influences have 
been regarded as readily conveyed by the atmosphere, and 
obscure or occult effects not comprehended or else mis- 
understood have been attributed naturally enough to the 
omnipresent and always-moving atmosphere. It is one of 
the merits of the germ theory of infectious disease that it 
enables us to comprehend much more clearly than ever 
before the true nature of these supposed atmospheric influ- 
ences. From what has just been said in the last paragraph, 
it is easy to see that the atmosphere may under certain cir- 
cumstances be a ready carrier of infectious disease simply 
by serving as the vehicle for the floating organic matters 
and living particles which are lifted into it from the surface 
of the earth or from human bodies. Doubtless it is with 
these very much as it is with the birds of the air or the 
flying fish of the sea, which, caught up or springing from 
the earth or the sea, may for a longer or shorter time float, 
fly or swim in the atmosphere, but which after all belong 

1 Those who wish to pursue this subject further may consult with advantage 
Tyndall's " Essays on the Floating Matter of the Air," New York (Appleton), 
and Prudden's "Dust and its Dangers," New York (Putnams). 



THE ATMOSPHERE AND DISEASE 113 

to the earth and sooner or later return to it. It must not, 
however, be forgotten that the germs of the commoner con- 
tagious diseases, and especially of those known as "erup- 
tive," in which "peeling" of the skin occurs, may be and 
probably are often disseminated through the atmosphere, 
and that so much of truth existed in the primitive ideas of 
mankind. 

§ 6. — Microbes of the Air 

The number of microbes in the atmosphere varies 
greatly. 1 In a dust-storm five feet above the surface of a 
macadamized street the author and one of his pupils, Mr. 
(now Dr.) John A. Rockwell, Jr., detected in ten litres 
of air two hundred thousand micro-organisms. Quiet air 
is usually relatively free from them (sewer air, for exam- 
ple, being often nearly or quite destitute of microbes), and 
the same is true of the atmosphere at high altitudes and in 
mid ocean. Even the expired air of the human lungs is 
quite free from germs, a fact doubtless due to the spongy 
and moist pulmonary surfaces which catch and detain in- 
coming microbes and a phenomenon of great interest and 
importance in the theory of infection. 

It is impossible to conceive of any other source or sources 
of infectious disease in the atmosphere than microbes." On 
the other hand, there is no difficulty in supposing that the 
ground air, rising and mingling with the ordinary atmos- 
phere, especially in periods of low barometer ; the gaseous 
exhalations of marshes, volcanoes, and the like ; the results 

1 The presence of microbes in the air is easily demonstrated, and their 
number enumerated, by various methods described at length in works on 
bacteriology. One of the simplest methods is that devised by the author and 
Mr. (now Professor) G. R. Tucker. It consists in filtering a known volume 
of air through fine sugar or sand — the latter having been found by experience 
to be preferable — by means of an exhausted cylinder and a glass tube of 
special form, called an aerobioscope, capable of being converted at will into a 
" roll " tube. The micro-organisms are held back by the sand, and together 
with the latter are mixed with melted gelatin during the rolling process and 
afterwards incubated, cultivated, enumerated and studied. 



114 0N FILTH AND THE PHILOSOPHY OF CLEANNESS 

of decomposition of dung-heaps, filth and other masses of 
decaying organic matter may, under certain circumstances, 
act as unfavorable environmental conditions and reduce 
the vital resistance to such a point that disease, which 
would otherwise have been absent, occurs. This simple 
view probably includes all or nearly all of the facts relat- 
ing to the atmosphere, strictly so called, as a source of 
disease, and probably suggests the true explanation of 
diseases supposed to be due to miasms, pestilential vapors, 
atmospheric and telluric influences, and the like. Even 
malaria, which has long been a puzzle to sanitarians, is 
apparently due not to any peculiar evil quality or disturb- 
ance of the atmosphere, such as the word implies, but 
rather to specific micro-organisms conveyed by the latter 
either directly as floating particles, or indirectly through 
insects or other living agents of transmission moving in or 
through the air (see pp. 94-96). Malaria has often been 
called paludism or swamp fever ; but if the modern view is 
correct it is not swamp air, but swamp insects (mosquitoes), 
which under favorable circumstances transport the germs 
of paludism. 

§ 7. — Filth Diseases. The Pythogenic Theory. Modern 
Views of Filth and Filth Diseases 

The principles which have been laid down in the pre- 
ceding chapters enable us to take up with regard to filth 
diseases a somewhat different view from that held in the 
third quarter of the nineteenth century. The term " filth 
diseases " was at that time used with the idea that filth 
might be not only a vehicle, but an actual breeder or gen- 
erator of infectious disease. This view even reached the 
dignity of a theory bearing a special name — the " pytho- 
genic " theory, — which is closely associated with the name 
of Murchison. According to Murchison, filth was danger- 
ous not merely because it was a vehicle of disease, or an 



THE " PYTHOGENIC " THEORY OF DISEASE 115 

unfavorable condition, but also because it was a source of 
disease, the supposition being either that specific disease 
germs could be generated de novo from other germs in 
filth, under favorable circumstances, or that at least germs 
capable of producing disease found in filth the conditions 
for their more perfect development, some even requiring 
residence for a time in filth in order to reach their full 
maturity. In regard to typhoid fever, for example, it was 
held that the micro-organisms of the disease required a 
stay, longer or shorter, in the earth or heaps of filth, and 
only after such a period attained their natural and dan- 
gerous development. The older treatises on typhoid fever 
and the older teaching often referred to a residence in the 
earth as one phase in the ordinary development of the 
germs of typhoid fever. 

The pythogenic theory requires some consideration at this point, as 
it lies at the basis of much popular misconception of the origin of 
infectious disease and, by misleading, causes a neglect of the true 
sources of disease. It was first propounded by Murchison in a foot- 
note to a paper read before the Royal Medical and Chirurgical Society 
of London, April 27, 1858 {Med. Chirurg. Trans. 1858, p. 221): 
" In the course of this essay I shall bring forward what I consider 
positive proofs that this fever [typhoid] is produced by emanations 
from decaying organic matter, and I would therefore suggest for it the 
appellation of pythogenic fever — 7rv0oyevrj<; and yewaa>." 

Murchison's views were urged at great length and with much plausi- 
bility in the first edition of his work (1862) on continued fevers, in 
which occur statements like the following : "Pythogenic [typhoid] 
fever is often generated spontaneously by faecal fermentation" (p. 455). 

The doctrine was vigorously criticised and opposed by the "con- 
tagionists," especially by Dr. William Budd of Bristol, and in the 
second edition (1873) of Murchison's "Continued Fevers" was con- 
siderably modified and restricted, although we find in that the follow- 
ing definition of pythogenic [typhoid] fever : "An endemic disease 
generated and propagated by certain forms of decomposing organic 
matter" (p. 417). And again : "It may be generated independently 
of a previous case by fermentation of faecal, and perhaps other, forms 
of organic matter. It may be communicated by the sick to persons in 
health, but even then the poison is not, like that of smallpox, given of? 



Il6 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

from the body in a virulent form, but is developed by the decomposi- 
tion of the excreta after their discharge. Consequently an outbreak 
of enteric [typhoid] fever implies poisoning of air, water or other 
ingesta with decomposing excrement." 

In these statements it is easy to see that Murchison was a believer in 
the spontaneous generation of specific disease in or through filth, an idea 
unfortunately still widely prevalent, but wholly without foundation in 
fact. In regard to a closely related infectious disease typhus (jail fever, 
ship fever, spotted fever), which has often been attributed to filth as a 
source, whereas filth is probably only its efficient vehicle, Murchison 
went even further, asserting its spontaneous origin in such conditions as 
overcrowding and bad ventilation : " Typhus, the grand predisposing 
cause to which is destitution ; while the exciting cause or specific 
poison is generated by overcrowding of human beings with deficient 
ventilation" (Edin. Med. Journ., 1858, p. 322). 

The modern theories of filth and its dangers are very 
different from these. Filth is first and always a conven- 
ient vehicle of disease ; but as a rule, in temperate climates, 
it is probably nothing more than this unless it be also a de- 
pressing, or unfavorable, "predisposing" condition. The 
earlier view which saw in filth a necessary phase in the 
life-history of certain infectious micro-organisms is now 
abandoned, and it is to-day very doubtful whether the germs 
of most infectious diseases ordinarily find accumulations of 
filth suitable for their multiplication. There is no question 
that the micro-organisms of disease may under favorable 
conditions occur or survive for a long time in filth, and it 
is probable that under certain conditions of warmth, food- 
supply and the absence of enemies they may even multiply ; 
but it appears probable that such conditions do not often 
occur in nature, unless perhaps occasionally in tropical coun- 
tries. The most natural and the most favorable means for 
the conveyance of disease germs appears to be that which is 
quickest and most direct, namely, contagion, or the transfer 
directly from one individual to another without the inter- 
position of the earth, the atmosphere or other extraneous 
influences. Contrary to Murchison's view, the longer the 
journey, and the more the time spent in making the jour- 



FILTH AND FILTH DISEASES \\y 

ney, from patient to victim, the less is the likelihood of the 
successful transmission of the disease. The interposition 
of filth or earth or air or water doubtless tends in most 
cases to the diminution of danger, owing to the unfavorable 
conditions of one sort or another encountered by the germs 
en route. 

Filth is looked upon by the sanitarian of to-day, there- 
fore, as dangerous chiefly because it may contain the more 
or less attenuated germs of disease, and not so much as 
formerly because it may be a "breeding-place" for such 
germs. It is a vehicle rather than a source ; and when it 
is pulverized it may cause an atmosphere in its vicinity to 
become infected ; or when handled it may find its way to 
the mouth, or when occurring upon fruits, vegetables, in 
milk, in water or any other substances likely to enter the 
mouth without having first been sterilized, — and in all 
these cases it is obviously dangerous as a vehicle. 

With these views of filth and its sanitary significance 
the older notions of " filth-diseases " have faded away. 
Those diseases to-day are simply ordinary, zymotic (infec- 
tious) diseases in which the vehicle of the causative germs 
is filth of some sort. 

§ 8. — The Philosophy of Cleanness 

From what has now been said, it is easy to perceive the 
modern philosophy of cleanness. Dirt is dangerous, not 
because it is " of the earth, earthy," but because it is too 
often " drit" or excrement; and the love of cleanness or 
the abhorrence of dirt, which is gradually becoming estab- 
lished in all highly civilized peoples, is doubtless a result- 
ant of the dearly bought experience of the race, which has 
shown that dirt is dangerous and therefore to be dreaded. 
Cleanness, or the absence of dirt, is not merely an aesthetic 
adornment, — though doubtless an acquired taste ; it is 
above all a sanitary safeguard, the importance of which 



Il8 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

has been learned by hard experience. In other words, to 
be clean is, in a measure, to be safe from infectious disease ; 
and cleanness applies not only to the person but extends 
also to the personal environment, and especially to the 
food supply, the water supply, the milk supply, etc. 

Probably, the greatest sanitary step ever taken by the 
race was the application of high temperatures to the prepa- 
ration of food, i.e. cookery. There is very little doubt 
that far more important than any increase in the digesti- 
bility of food effected by cookery is the destruction of 
parasites, visible and invisible, within it thus brought about. 
Charles Lamb was probably right in attributing the love 
of cookery to the improvement in the flavors of food which 
it occasions, as is described in his well-known version of the 
discovery in the case of roast pig ; and yet there is every 
reason to believe — as has only lately become recognized — 
that the sanitary improvement wrought by the discovery 
of cookery was even more important than either the 
gustatory or the nutritive improvement. It is difficult to 
see how infection could have been otherwise than very 
common and very disastrous before the invention of cook- 
ery, for even to this day uncooked food forms one of the 
principal vehicles for the conveyance of parasites and 
disease germs. 

§ 9. — Personal versus Public Cleanness 

It follows as a matter of course that personal cleanness 
is more important than public cleanness. In other words, 
that the avoidance of personal filth is far more necessary 
than, for example, is cleanness of streets, dooryards, alleys 
and the like. And yet, as is pointed out and emphasized 
beyond (p. 221), public supplies are public dangers. If 
the public water supply, for example, be infected, no 
matter how scrupulously clean the residents of a city may 
be in respect to their persons, they will run very serious 



THE SANITARY SIGNIFICANCE OF COOKERY 119 

risks of disease if they drink from it. The same thing 
may be said of the public milk supply; and nothing is 
more impressive to the practical sanitarian than to witness 
an epidemic of typhoid fever in a wealthy and well-cared- 
for quarter of a city, where the inhabitants are personally 
clean, the houses are unexceptionable, the plumbing per- 
fect, the drains in good condition, the tableware and linen 
spotless, and yet typhoid fever is present perhaps in 
nearly every family, because of a polluted and infected 
milk supply or water supply. It must never be forgotten 
that the sanitary chain is no stronger than its weakest part, 
and that, no matter how clean and wholesome all other 
conditions may be, if there is one point from which the 
germs of infectious disease may find admission into the 
body, danger may be imminent. Nothing is more instruc- 
tive than to discover cities or towns in which great com- 
plaint is made of filth in the streets, — from which, after 
all, comparatively little danger is likely to come, — while 
an impure water supply or milk supply is being used with 
absolute confidence, or blindness, or ignorance. 

§ 10. — Public Drinking-cups and their Dangers 

It not infrequently happens that the same persons who 
complain loudly and rightly enough, perhaps, of dirty streets, 
and are quick to blame public officials for their laxity 
in this respect will, nevertheless, at fountains, in railway 
trains or in theatres, apply their own lips to public drink- 
ing-cups which a few minutes before have been touched 
by the lips of strangers, possibly suffering from infectious 
diseases, such as tuberculosis or diphtheria. It should 
require only a moment's consideration to show how great 
is the risk run under these circumstances, and how 
inconsistent is the criticism bestowed by one who thought- 
lessly takes these grave risks when he cries out at the 
relatively remote dangers of dirty streets. What has been 



120 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

said about drinking-cups applies obviously to communion- 
cups, "roller" towels, razors in barber shops, unclean 
dishes, spoons, etc., and requires no further comment. 
The dangers of these things are too obvious to need 
emphasis. A sanitary fountain has been devised, and is 
in use in many places, to do away with the public drink- 
ing-cup, and in so far as it is successful in doing this, 
it deserves the warm commendation of sanitarians. The 
arrangement by which this is accomplished is very simple ; 
and for use in public places, schools, institutions and the 
like, it promises to be of great assistance. No cup what- 
ever is required, but any one who wishes simply leans over 
and drinks from a little fountain provided for the purpose. 
Every instant, of course, the water supply is changing, and 
if infectious micro-organisms should be for an instant 
deposited by A, they are necessarily the next instant 
washed away before B can come in contact with them. 
It has long been the custom in certain factories abun- 
dantly supplied with water, to keep rising, in the middle 
of a basin of convenient height, a small jet of water, from 
which the thirsty might drink. Small fountains of this 
kind can easily be arranged in many public places, doing 
away altogether with the common drinking-cup, which, 
wherever found, is a sanitary abomination. 

§ ii. — The Disposal of Dirt, Dust, Garbage and Refuse 

From the point of view of the sanitarian the disposal of 
garbage and refuse is largely a question of engineering. 
By " garbage " is usually meant the more solid organic 
wastes of the kitchen, the more liquid wastes being dis- 
charged through the sink- pipe into the sewer. By " refuse" 
is meant household wastes such as dirt, ashes, papers, 
boxes, dust, bottles and the like, which are only in part 
combustible. It is from the sanitary point of view de- 
sirable to get rid promptly and effectually of both garbage 



MUNICIPAL SANITATION 121 

and refuse, for these may contain the germs of infectious 
disease, and their destruction or disinfection by fire — the 
quickest and most certain of all disinfectants — is highly 
desirable. What is not desirable is that garbage should 
be fed to cows used as sources of milk supply, not because 
of the dangers of infection, but because of the poor quality 
of milk likely to result. There is less objection, if any, to 
the disposal of garbage by feeding it to swine, or by carry- 
ing it to sea or by ploughing it into the living earth, which 
latter readily disposes of it as of stable manure. Various 
methods for the disposal of garbage and refuse are in use; 
but while cremation, for the reasons given, is undoubtedly 
the most desirable, the sanitary aspects of the matter do 
not appear to be especially important so long as garbage 
and refuse are removed from dwellings or groups of dwell- 
ings, such as cities, and somehow effectively disposed of. 
Those who desire to enter further into this subject may be 
referred to Chapin's " Municipal Sanitation in the United 
States," Providence, R. L, 1901 ; to Goodrich's " Disposal 
of Town's Refuse," N. Y. (Wiley) ; London (P. S. King), 
1 90 1 ; and to Baker's " Municipal Engineering and Sani- 
tation," N. Y. (Macmillan), 1902. 

§ 12. — Cleanness, Asepsis and Antisepsis 

Inasmuch as dirt is richly laden with micro-organisms, 
the agents of fermentation, putrefaction and decay, it is 
plain that the absence of dirt, or cleanness, must go far to 
prevent these processes. It is clear, for example, that 
punctures of the skin made by instruments absolutely free 
from organisms cannot convey infection ; that the knife of 
the surgeon if absolutely clean cannot cause "dissecting 
wounds " ; that cookery of foods must tend to defer their 
decay: in short, that absolute cleanness is equivalent to 
asepsis, and partial cleanness is an antiseptic correspond- 
ing in efficiency to its extent. This is now so fully recog- 
nized that dirt is to-day regarded as the principal foe of 






122 ON FILTH AND THE PHILOSOPHY OF CLEANNESS 

the surgeon; and probably the cleanest rooms that have 
ever been known either in modern times or in the past, are 
the operating rooms of the hospitals of to-day. 

In certain industrial pursuits experience is teaching a 
similar lesson. By drawing milk from healthy cows with 
extreme precautions as to cleanness, it is possible to have it 
keep sweet (if refrigerated) during the whole period of a 
trans-Atlantic voyage. Various other dairying processes 
are also favored, if not conditioned, by cleanness ; can- 
ning and preserving are far more successfully carried 
out if done with scrupulous regard for cleanness ; and it 
is no exaggeration to say that in all human affairs clean- 
ness — which means the exclusion or destruction of germ 
life — is the keynote of successful sanitation. 



CHAPTER VII 

ON SEWAGE AS A VEHICLE OF DISEASE. ITS PROPER DIS- 
POSAL AND PURIFICATION. THE NATURAL PURIFICATION 
OF SEWAGE BY FERMENTATION AND THE LIVING EARTH 

" If we neglect this subject, we cannot expect to do so with impu- 
nity." — Michael Faraday, on " The Filth of the Thames. 11 London, 
1854. 

" The sewer ... is, so to speak, the direct continuation of the . . . 
intestine. 11 — William Budd, on "Typhoid Fever. 11 London, 1873. 

"The bills of mortality are more obviously affected by drainage 
than by this or that method of practice." — Oliver Wendell 
Holmes, on "Border Lines of Knowledge, 11 etc. Boston, 1862. 

§ I . — The Disposal and Disinfection of Excreta 

Since there is reason to believe, as has been shown in 
Chapter V, that the excreta of man and other animals are 
the principal original vehicles of infection and contagion, 
one of the first problems of sanitation is the safe disposal 
and disinfection of excreta. Various devices for the dis- 
posal of the wastes of animal life have had their day, but 
only two need now be mentioned, viz., the " dry-earth " 
system and the " water-carriage," or "sewerage," system. 
The former was at one time in high repute, and in some 
cases, as in farm-houses, country-houses, and villages, is 
still useful, especially if water is scarce or difficult to get. 
It is open, however, to the grave sanitary objection that 
although dry earth deodorizes well, it does not necessarily 
disinfect ; while on the practical side the system is much 
less convenient than disposal by water-carriage. The in- 
troduction of running water for other purposes, even into 
farm-houses and villages, has also greatly favored disposal 

123 



124 0N SEWAGE AND ITS PURIFICATION 

by sewerage ; so that the windmill and the cesspool have 
made unnecessary almost anywhere either the earth-closet 
or the privy. 1 In view of the now limited use of the dry- 
earth system we need not dwell upon it further. 

In the water-carriage (or sewerage) system, which is 
now so generally adopted and so familiar as to require no 
description the vehicle of infection is sewage. This sub- 
stance is of special and fundamental importance in sani- 
tary science, first, because of its character as a common 
carrier of excreta and a vehicle of infection; second, 
because of its ubiquity and abundance in modern life; 
and third, because it may contain not only the bowel 
discharges and urine of the diseased, but also the excreta 
from the mouth and the skin. In brief, sewage may be 
made up of all the original vehicles of disease, — the 
excreta from the skin; from the alimentary and pul- 
monary, and from the genito-urinary tracts ; and it is also 
subject to indirect infection from infected earth, air and 
water serving as secondary vehicles. 

The cleansing and disinfection of sewage is commonly 
described as its " purification," but before proceeding to 
consider this problem, one of the most pressing and one 
of the most difficult of the sanitary arts, we must inquire 
somewhat more closely concerning the nature of sewage, 
its origin and its fate. 

§ 2. — Sewage : its Genesis and Composition 

The word " sewage " 2 signifies " drainage " and may be 
defined as the contents of drains ; but it must be distinctly 

1 For an elaborate defence of the sanitary efficiency of the Dry-earth Sys- 
tem, see Buchanan, Twelfth Ann. Rep. Med. Off. Privy Council, 1869. Per 
contra, see Sinnhuber, Inaug. Diss. Konigsberg, under Esmarch. Baumgarten's 
Jakresbericht, XII (1896), 844. 

2 In common parlance the terms " sewage " and " sewerage " are often 
confounded. It is usual, however, as it is certainly preferable, to reserve 
the latter for the system of sewers, and to use always the word " sewage " for 
the liquid contents of sewers. 



SEWAGE VS. SEWERAGE 



125 



understood that the drains in this case shall be house drains 
and shall contain domestic drainage. The under-drains of 
a wet piece of uninhabited land, for example, contain 
drainage but no sewage, the idea of sewage being con- 
nected exclusively with the drainage of houses and human 
beings, or at least with the wastes of animal life. Sewage 
is composed ordinarily of the washings of sinks, the empty- 
ings of water-closets, the discharges from laundries, bake- 
shops, stables and similar places, together with the 
rain water from roofs and the washings of streets. It 
may also contain the refuse from slaughter-houses, pus 
and other substances from hospitals, the washings of 
markets — in fact, almost anything capable of carriage by 
water, and small enough to find entrance into sewers. 
The excreta of human beings, washings from the skin, 
sputum, bowel discharges, urine, — in short, all excreta 
excepting the breath, — may be present in sewage. 

Nevertheless, ordinary American sewage, on account 
of its vast dilution, is much less objectionable to look 
at than is commonly supposed and it often merely sug- 
gests in appearance dish-water or dilute milky liquids 
with some dirt in suspension. The average composition 
of the fresh domestic sewage of an American city (Law- 
rence, Mass.) for 1897 was, during the morning, when 
the sewage was relatively strong, as follows (parts per 
100,000): — 



i* 


Albuminoid Ammonia 


w 
z 
5 

3 

X 

u 


Nitrogen as — 


Z a 
H s 

°3 


u 


K * 
fa 


Total 


Soluble 


Insoluble 


Nitrates 


Nitrites 


Bact 

PER 

Cen 

MET 


3.19 


I.26 


.78 


.48 


13.36 


.18 


.Ol82 


7-59 


4,726,000 



The sewage of European towns is usually much more 
concentrated than that of American cities, and is there- 



126 ON SEWAGE AND ITS PURIFICATION 

fore darker in color, less watery or milky and more 
objectionable in appearance. 

§ 3. — The Dangerous Elements and Properties of Sewage 

These consist chiefly in the disease-producing organisms 
which may be present. There is every reason to suppose 
that sewage free from such organisms might be swallowed 
without serious harm, and would be rather in the nature 
of a poor than a dangerous material. Inasmuch, however, 
as sewage contains or may contain the excreta of human 
beings or other animals, and inasmuch, further, as has been 
shown above, as it is by way of these excreta that infec- 
tion travels, sewage must always be regarded as dangerous, 
either to come into contact with, or to admit into the body 
through wounds, or in or upon food materials. There is 
reason to believe that the only really dangerous properties 
of sewage reside in the infectious elements referred to. 
The ordinary decomposition of sewage may indeed lead to 
the generation of objectionable gases, which shall tempo- 
rarily prejudice or damage the organism. But there is 
every reason to believe that the dangers of sewer gas have 
been much exaggerated, and that many cases of disease 
have been charged to sewer gas which were really due 
to the invasion of micro-organisms from other and very 
different sources. To the consideration of this question 
however, we shall return hereafter (Appendix, p. 347). 

§ 4. — Importance of the Sanitary Disposal of Sewage 

Inasmuch as sewage may at any time contain any or all 
of the excretions of the animal body, and inasmuch further 
as these may contain actively infectious materials, the safe 
and proper disposal of sewage is one of the first necessi- 
ties of sanitary science and the public health. Among 
primitive and uncivilized peoples no special pains are taken 
for the disposal of sewage or the excreta of animals, but 



PRIMITIVE METHODS OF SEWAGE DISPOSAL 12? 

in civilized societies various and costly devices are em- 
ployed to this end. The most primitive method is that in 
which the wastes of life are simply deposited or thrown 
out upon the surface of the earth in the neighborhood of 
human habitations, and when the latter are widely separated 
little or no harm may result from this practice. When, 
for example, in country districts or elsewhere, the untidy 
housewife disposes of dish-water by simply throwing it 
from a window, no particular harm may result if the quan- 
tity thus disposed of is not too great, and the dousing of 
the soil below is not too frequent, especially if the soil 
be open, porous or sandy. We shall shortly see that 
in this case, and in the similar cases in which manure is 
applied to land in large quantities and in successive years, 
the organic wastes present are speedily mineralized or 
converted into inorganic matters, by the agency of bacteria 
residing in the soil in such overwhelming numbers as to 
form a density of population almost inconceivable, and 
entitling us to describe the surface layers of the earth as 
" the living earth." 

§ 5. — Disposal of Sewage in Rivers 

Whenever a city or town introduces a system of sewers, 
it is easy and natural in many cases to dispose of the sew- 
age by simply letting it run from the principal sewer or 
sewers into a neighboring brook or river or other stream. 
It is easy, because the natural drainage is in the direction 
of the river, which is often little more than the principal 
natural drain of the neighborhood. It is natural, because 
the river being, as stated, the ordinary drain of the neigh- 
borhood, carries off not only the water which falls upon 
its watershed but also anything that will float upon or 
mingle with the water ; and in most cases even before it is 
proposed to introduce sewers, the stream has long been 
used as an easy means of ridding the neighborhood of 



128 ON SEWAGE AND ITS PURIFICATION 






rubbish or wastes of various descriptions. It cannot be 
denied that, in case the amount of sewage to be got rid 
of is relatively small, and provided the stream is nowhere 
below used as a source of water supply, this practice may 
not necessarily be objectionable; but even in such cases it 
is generally unwise, because under slightly different condi- 
tions, such as growth of the population upon the water- 
shed, or unexpected drought, the presence of a relatively 
large amount of sewage may produce a nuisance, and 
prejudice the public health, finally transforming the stream 
from something capable of giving pleasure, into an open 
sewer shunned by all mankind. 

How, then, it will naturally be asked, has it happened 
that so many important cities and towns all over the world 
freely dispose of their sewage by simply turning it into the 
nearest watercourse ? The answer is easy. It is simply 
because until very lately engineers, chemists and sanitary 
experts, alike held as true a theory of the purification of 
watercourses which is now known to be false, or, at best, 
only a half truth. This was the famous theory of the " self- 
purification of streams," to a brief consideration of which 
we may now turn. 

§ 6. — Theory of the Self -purification of Streams 

This theory was based upon the obvious fact that al- 
though a very large amount of sewage might be suddenly 
poured into a stream at a given point, so that at that point 
the pollution was conspicuous and self-evident, it was only 
necessary to follow the stream for a short distance to per- 
ceive that the water had distinctly improved in appearance. 
This result of mere inspection was strongly confirmed by 
the chemistry of the time, which proved by actual analysis 
that the organic matter in the water, and the results of 
decomposition, were decidedly less at the lower than the 
upper point. Naturally, only one conclusion could be 



THE " SELF-PURIFICATION " OF STREAMS 129 

drawn from the premises. The stream had somehow puri- 
fied itself while flowing, and the corollary was deduced 
that "running water purifies itself." (Cf. p. 231.) 

The importance and far-reaching effects of this con- 
clusion can hardly be overestimated. Relying upon it, 
numerous cities and towns all over the world introduced 
water supplies derived from sewage-polluted streams, and 
infinite damage was done to the public health. The theory 
is now abandoned, or rather accepted only after so much 
modification that it is virtually new. There is, indeed, a 
considerable purification effected by streams, but it is 
mostly purification by dilution ; and, as we shall see in a 
later paragraph, distrust of this theory has produced pro- 
found changes in our points of view. The disposal of 
sewage in rivers is always to be deprecated unless the 
volume of sewage discharged is very small in proportion 
to the dry weather flowage of the stream in question. It 
is not to be tolerated if the river below is, at any point, 
however remote, used without purification as a source of 
water supply ; and it is often not desirable even with such 
purification. 

§ 7. — Sewage Disposal in Lakes 

Some cities are so situated that it is convenient and 
natural for them to drain into bodies of fresh water, either 
lakes or ponds, in which there is little or no current 
such as always exists in a river. In these cases, the suc- 
cess of the practice, so far as the mere disposal of sewage 
goes, depends chiefly upon the proportion maintained be- 
tween the volume of sewage and the volume of the water 
into which it is discharged. This will be seen most clearly 
by simply considering the extremes, in which cases, for 
example, a large city empties its sewage into a small pond ; 
or, on the other hand, a small town pours its sewage into 
a large lake. In the former case, the results would be 
disastrous, the pond being very soon converted into a sew- 



130 ON SEWAGE AND ITS PURIFICATION 

age pool. In the latter, no perceptible effect would be 
produced. Obviously, there must be a large class of cases, 
comprising cities and towns of moderate size located upon 
relatively large bodies of quiet water, which may drain with 
safety into lakes or ponds ; but it is equally clear that there 
is also another class of cases, comprising for the most part 
large cities, situated upon relatively small bodies of quiet 
water, which cannot drain into these without seriously 
prejudicing their purity and possibly producing a nuisance. 
Furthermore, the case is complicated seriously if either 
a city or a town draining into a lake or pond undertakes to 
derive its water supply from the same lake, or if any other 
city or town, no matter how remote, makes such use of 
the water. This aspect of the problem, however, need not 
detain us at this point but may be reserved for the con- 
sideration which it requires until a later chapter. It is 
enough in this connection to note that very many of the 
cities and towns of the United States do as a matter of 
fact dispose of their sewage by emptying it into lakes or 
ponds, and that, too, with entire success so far as the mere 
disposal of the sewage alone is concerned. Examples are 
the cities and towns bordering the Great Lakes, and in the 
list are some cities of large size such as Chicago, Mil- 
waukee, Duluth, Cleveland and Toronto. 

§ 8. — Disposal in Harbors ', Estuaries and the Sea 

Another class of cities and towns, and this includes some 
of the largest in the world, are so situated that their natural 
drainage is either directly into the sea, or into some tidal 
harbor or estuary. In these cases it is easy and natural to 
dispose of sewage by simply pouring it into the sea, harbor, 
or estuary at some convenient point or points ; and here, 
also, as in the preceding case, if the city or town is not too 
large in proportion to the volume of water at its doors, no 
harm comes from such disposal. There is, in this case, 



SEWAGE DISPOSAL IN LAKES AND THE SEA 13 1 

the obvious advantage that such bodies of water are never 
used as sources of water supply, so that one serious ele- 
ment of difficulty which exists in the case of lakes and 
other bodies of fresh water may here be neglected. As 
a matter of fact, numerous cities and towns on our own 
coasts pour their sewage into salt or brackish waters, often 
with entire success and with the absence of all complaint. 
It is only, indeed, in very rare cases, that this system of 
disposal causes trouble, and in these instances the cities 
are usually situated not directly on the sea itself, but upon 
some narrow arm of the sea or some tidal river which 
virtually limits the size of the body of water into which 
the sewage is poured. Such a case is that of London, 
which is situated not upon the sea, but upon a tidal river, 
and even in the case of London the sources of complaint 
have been based more upon the alleged obstruction to 
navigation caused by deposits in the shallow river than 
upon sanitary grounds. No such complaints, at least of 
a serious character, have as yet arisen in the case of cities 
like New York, Philadelphia or Boston, or indeed, so far 
as the writer is aware, in any instance excepting that of 
London ; so that we may probably conclude that disposal in 
the sea or in its harbors or estuaries may safely be regarded 
as one of the most satisfactory methods of sewage disposal 
hitherto discovered or employed. 

§ 9. — Principles involved in the Disposal of Sewage in 
Rivers, Lakes, Estuaries and the Sea 

In all these cases the fundamental principle of purifica- 
tion, and the basis of successful disposal, is simple dilution, 
by a relatively large volume of purer water. Other factors 
may or may not cooperate as, for example, in the case of 
a swiftly flowing river. The mere fact of removal some- 
times constitutes an important contribution to successful 
sewage disposal, the sewage being speedily carried away 



132 ON SEWAGE AND ITS PURIFICATION 

to a point where its existence is of little consequence, as 
for example, may happen in an estuary or tidal river, the 
mere movement of the water constituting an efficient 
method of transportation of the sewage from a point 
where it would be objectionable to a point where its pres- 
ence is unobjectionable. But this is not all. Dilution is 
the fundamental phenomenon, and lies at the bottom of 
much of the purification which, undoubtedly, takes place in 
all these cases. Mere removal does not, in itself, contrib- 
ute to purification, while dilution certainly does do so. 
There are, however, other forces at work which contribute 
materially to purification by dilution, and these are best 
seen and studied in the case of the discharge of sewage 
into the relatively quiet waters of a lake, where they are 
not complicated or masked by currents, or by the flowing 
of a stream. Such instances are common and easily 
studied, and, as an example, we may take the case pre- 
sented by the sewage disposal of Burlington, Vt. (Cf. 

P- 234-) 

Burlington is a city of fifteen thousand inhabitants, situ- 
ated on Burlington Bay, a broad easterly expansion of 
Lake Champlain. The sewage of the city is collected into 
one large outfall sewer which empties near the southern 
extremity of the city directly upon the lake front into the 
waters of the lake. At this point Lake Champlain is so 
broad that the only currents perceptible are those produced 
by winds, and, accordingly, these move sometimes in one 
direction, sometimes in another, but as a rule are confined 
to the surface, so that, on the whole, there is very little 
motion of the lake water in any particular direction. The 
author has made repeated examinations of the sewage in 
the outfall sewer and of the mixed water and sewage at 
various points within one mile of the sewer outlet, and the 
results show that while the crude sewage is not materially 
different from that observed in most American cities, and 
contains in round numbers about one million of bacteria 



SEWAGE PURIFICATION BY DILUTION, ETC. 133 

per cubic centimetre, the lake water even one hundred feet 
away shows already only perhaps a thousand, which num- 
ber rapidly declines as we recede from the sewer, until at 
a distance of a half mile and more it begins to be difficult 
to find any evidence of the presence of sewage, either 
by chemical or by bacteriological analyses. 

A little reflection will show that the mere dilution of 
the relatively small amount of sewage by the relatively 
enormous volume of the lake would alone account for most, 
if not all, of the facts in the case. But there is good 
reason to believe that other factors of purification exist and 
have their influence. In the first place, many of the sewage 
bacteria, and probably all of the most dangerous, are by 
preference thermophilous, or, so to speak, warm-blooded, 
having recently come from the bodies of warm-blooded 
animals in which they have existed and perhaps thriven. 
These, therefore, find the temperature of sewage hardly 
favorable to their continued existence or development, and 
when plunged into the still colder waters of the lake are 
subjected to conditions far less favorable. In the next 
place, in the bodies of their hosts these bacteria have found 
not only a favorable temperature, but also rich supplies 
of food. Once they begin to travel through soil pipes and 
sewers, their food becomes scarcer and less available, and 
when finally they mingle with the waters of the lake, 
which are relatively pure and destitute of organic matters, 
their pabulum must be distinctly scanty. At the same 
time, in sewage and in the lake, they are subject to the 
influence of gravity which tends to draw them down into 
the deeper, quieter layers and finally into the mud at the 
bottom, while predatory infusoria ranging through the 
water may devour them altogether. Lastly, if they tend to 
float or linger on the surface, they may there suffer from 
the germicidal action of the rays of light and perish. 

All of these unfavorable influences which accompany 
the ordinary process of dilution in lakes, rivers, estuaries 



134 ON SEWAGE AND ITS PURIFICATION 

and the sea may be either hindered or exaggerated by 
movement of the water, such as occurs in a flowing stream, 
or in tides and other currents, and they, and all other con- 
ditions tending to the inhibition of the growth, or to the 
destruction altogether, of microbic life, may all be summed 
up in one phrase, namely, "unfavorable environment." 
There is reason to believe that the purification of sewage 
by dilution, in respect at least to its living, organic con- 
tents, is, as a matter of fact, considerable, though often 
incomplete, and that the forces enumerated and which we 
have described collectively as " unfavorable environment " 
play the principal part in whatever purification actually 
takes place. Inasmuch, however, as many micro-organisms 
are capable of successfully resisting for a long time the 
effects of an unfavorable environment, bacteria being in 
some cases especially resistant, it is easy to understand 
that the purification of sewage by dilution, even when 
accompanied by the factors mentioned, is often incomplete 
and never to be relied upon, except in the presence of sat- 
isfactory evidence. In the case of sewage disposal in salt 
water this is a refinement of small consequence, but in the 
case of fresh waters, such as lakes and rivers, which it may 
be desirable to use for public water supplies at points 
more or less remote from the place of disposal, the ques- 
tion assumes the highest possible importance, and to this 
aspect of the subject we shall return in Chapter IX. 

§ 10. — Purification of Sewage by the Living Earth 

Reference has already been made above, in § 4, in 
some detail to the primitive method of sewage disposal 
in which the wastes of life are got rid of by simply 
throwing them upon the earth. In this case, and in the 
similar case in which manure is applied to land in large 
quantities and for many successive years, the organic 
wastes present are speedily mineralized, or converted into 



SEWAGE AND THE LIVING EARTH 135 

inorganic matters by the agency of micro-organisms (bac- 
teria) which reside in the surface layers of the earth in 
astonishing numbers. 

The commonly received idea of the earth, that it is 
typically inorganic and lifeless, has been shown by modern 
researches to be singularly incorrect. Every one is aware 
that various living things, such as woodchucks, moles, 
snakes, and even certain birds, as well as numerous insects 
and innumerable plants, spend a part or the whole of their 
existence in the earth. And yet, when, in 188 1, Darwin 
drew general attention to the enormous number of earth- 
worms living in the upper layers of the earth, his treatise 
occasioned widespread surprise. All these forms of life, 
however, are as nothing in comparison with the myriads 
of bacteria which have their home in the earth. A single 
grain of garden soil, for example, may contain as many as 
a hundred thousand of these microscopic organisms, and 
there is reason to believe that the soft, clammy feel of 
moist loam is in no small measure due to the presence of 
bacterial bodies. In many cases the inorganic grains 
which loam contains are mantled, as it were, by a jelly- 
like substance, probably produced by these organisms, and 
in which their bodies are embedded. It is no exaggera- 
tion, therefore, at present, to speak of the surface layers 
of the earth, especially in fertile regions, as if they were 
alive, or of the upper layers of the earth itself as con- 
stituting a " living " rather than a lifeless earth. 

If now we consider what may take place when the 
organic wastes of life are thrown upon this porous, living 
earth, we may perhaps understand the remarkable process 
of purification which takes place. When, for example, the 
farmer periodically dresses his fields with manure consist- 
ing largely of the wastes of animal life, we need not be 
surprised if, after a time, these wastes seem to have dis- 
appeared, while the soil upon which they were placed has 
grown correspondingly soft and rich. Precisely as, under 






136 ON SEWAGE AND ITS PURIFICATION 

similar circumstances, the earthworms which are present 
appear to flourish and multiply under the favorable condi- 
tions provided for them by the farmer, so, we have reason 
to believe, the infinitely smaller micro-organisms — which, 
like the earthworms, reside in the upper layers of the 
earth, — feed, flourish and multiply upon the food thus 
provided for them ; and exactly as the earthworms work 
over the materials upon which they feed, reducing them 
in chemical complexity, and turning organic into inorganic 
matters, so the myriads of micro-organisms which surround 
them on every hand do their appointed work, and min- 
eralize the organic wastes upon which they too feed and 
fatten. 

If what has just been said is true, it is easy to under- 
stand how it is that even repeated applications of large 
amounts of organic matters, such as stable manure, may be 
successfully made to a given area of land ; or how it hap- 
pens that the untidy housewife may, with comparative im- 
punity and for a long period, habitually throw from the 
window upon a limited piece of earth the organic wastes 
of the kitchen ; or, finally, the fact that some of the larg- 
est cities in the world, such as Berlin, successfully dispose 
of all their sewage by simply pouring it upon the land. 
There is every reason to believe that this method of sewage 
disposal, which is successfully in operation under either 
natural or artificial conditions all over the world, is, at the 
same time, one of the most primitive, one of the most 
practical, and one of the most perfect, systems hitherto 
employed by man. We may, therefore, in the next para- 
graphs, properly devote considerable attention to its theory 
and practice. By a curiously unfortunate use of words 
this process has come to be known by the altogether 
inadequate term "intermittent filtration." As we shall 
now see, intermittent filtration lies at the basis of all- 
sewage disposal by irrigation and of all successful sewage- 
farming. 






LAND-DISPOSAL OF SEWAGE 137 

§ 11. — Intermitte?it Filtration 

In all cases of sewage disposal upon land, whether crops 
be grown upon the land or not, the fundamental processes 
at work are those involved in intermittent nitration, and 
this, as has been explained in the preceding paragraph, 
consists in biological and chemical treatment of, or reaction 
upon, sewage by the living earth. 

It has long been known that earth and soil are remark- 
ably effective in the purification of sewage. Everyday 
observation, such as that described in the preceding section 
in connection with the ordinary operations of agriculture, 
proves that land-disposal of organic wastes is perfectly 
natural and successful. The process, consisting as it does 
in a change of organic into inorganic matter, early attracted 
the attention of chemists, and inasmuch as the purification, 
chemically speaking, consists largely in oxidation of nitroge- 
nous bodies with conversion of the latter into nitrates, the 
essential phenomenon is often described as "nitrification." 

§ 12. — English Experiments on Intermittent Filtration 

At first it was supposed that nitrification was due to the 
direct action of the oxygen of the air upon complex nitroge- 
nous bodies, but it was soon perceived that something more 
must be at work. It was evident, for instance, that stable 
manure exposed to an abundance of oxygen in the air re- 
mained unaffected, while if it were brought into contact with 
the soil in the ordinary process of agriculture, it speedily 
disappeared, giving rise to nitrates in abundance. Labora- 
tory experiments showed further that the nitrification could 
readily be set up by introducing earth into mixtures which it 
was desired to nitrify, so that it seemed perfectly clear that 
somehow the earth possessed a specific, nitrifying power. 
Some supposed that this was due to its porous character 
which might produce oxidation somewhat after the fashion 
of platinum sponge. 



138 ON SEWAGE AND ITS PURIFICATION 

The first experiments on the disposal of sewage upon 
land or earth were laboratory experiments made by the 
Rivers Pollution Commissioners of Great Britain appointed 
in 1868, in connection with their investigations of the pollu- 
tion of rivers, and were most instructive. In these experi- 
ments, glass tubes, sixteen feet long and two inches in 
diameter, and glass cylinders, six feet long, and either ten 
and one-fourth or twelve inches in diameter, were filled 
with various kinds of soil. Each then received at the 
top (or in some cases at the bottom) known amounts 
of sewage which were discharged as effluent at the 
other end, and in the case of downward intermittent fil- 
tration were found to have been remarkably purified. A 
full report of these important investigations may be found 
in the First Report of the Rivers Pollution Commission 
appointed in 1868, published in 1870. (Mersey and 
Ribble Basins, Vol. I, pp. 60-70.) The facts developed 
by these experiments remained, however, largely unex- 
plained until a few years later when the investigations of 
other observers drew attention to the probable cooperation 
of micro-organisms in the processes of nitrification. More- 
over, the Commission's experiments were conducted on 
a laboratory scale, and were limited in number as well as 
in time. 

§ 13. — The Problem Attacked in Massachusetts 

It remained for the State Board of Health of Massa- 
chusetts to take up the problem where the Commission 
had left it, and to make for the first time extensive and 
elaborate experiments upon a large scale with the aid of 
bacteriology as well as chemistry, upon the purification of 
sewage by land treatment or "intermittent filtration." In- 
asmuch as these investigations were the first to be 
made on a large scale and for a long time, and inasmuch 
as they have now become classical, we may describe 



EARLY INVESTIGATIONS IN ENGLAND 139 

them, together with the conditions which led up to them, 
in some detail. 1 

The state of Massachusetts, especially in its eastern 
portion, had become, by 1880, so thickly settled that the dis- 
posal of the sewage of the numerous cities and towns com- 
posing the metropolitan district having Boston as its centre 
was becoming a serious problem. Accordingly, in 1881, 
a Commission was appointed to consider and report upon 
the drainage of the Mystic and Charles River valleys. 
The report of these commissioners recommended a metro- 
politan district system which should preserve as far as 
practicable by general sewerage the purity of the water 
supplies of the cities included in this district. In 1884 the 
Massachusetts Drainage Commission was appointed, and 
in 1886 their report was published, giving a large amount 
of valuable information regarding sewage disposal theories 
and practices in England and on the Continent. Perhaps 
the most important work which they accomplished, how- 
ever, was their earnest recommendation that the common- 
wealth of Massachusetts should appoint a Commission or 
designate Guardians to conserve the purity of the inland 
waters of the state, such body to be provided with advisory 
rather than mandatory powers. 

" Let these guardians of inland waters be charged to acquaint them- 
selves with the actual condition of all waters within the state as respects 
their pollution or purity, and to inform themselves particularly as to the 
relation which that condition bears to the health and well-being of any 
part of the people of the commonwealth. Let them do away, as far as 
possible, with all remediable pollution, and use every means in their 
power to prevent further vitiation. Let them make it their business to 
advise and assist cities or towns desiring a supply of water or a system 
of sewerage. They shall put themselves at the disposal of manufac- 
turers and others using rivers, streams, or ponds, or in any way mis- 

1 For an interesting and valuable historical statement of the rise and treat- 
ment of the drainage problem in a growing community, see Report of a Com- 
mission appointed to consider a General System of Drainage for the Valleys of 
Mystic, Blackstone, and Charles Rivers. Boston, 1886. 



140 ON SEWAGE AND ITS PURIFICATION 

using them, to suggest the best means of minimizing the amount of dirt 
in their effluent, and to experiment upon methods of reducing or avoid- 
ing pollution. They shall warn the persistent violator of all reasonable 
regulation in the management of water, of the consequences of his acts. 
In a word, it shall be their especial function to guard the public interest 
and the public health in its relation with water, whether pure or defiled, 
with the ultimate hope, which must never be abandoned, that sooner or 
later ways may be found to redeem and preserve all the waters of the 
State. We propose to clothe the board with no other power than the 
power to examine, advise, and report, except in cases of violation of the 
statutes. Such cases, if persisted in after the notice, are to be referred 
to the attorney general for action. Other than this, its decisions must 
look for their sanction to their own intrinsic sense and soundness. Its 
last protest against wilful and obstinate defilement will be to the General 
Court. To that tribunal it shall report all the facts, leaving to its 
supreme discretion the final disposition of such offenders." 1 

§ 14. — Reorganization of the State Board of Health of 
Massachusetts 

The legislature of 1886 promptly adopted the recommen- 
dation of the Drainage Commission, and turned to the 
State Board of Health as the proper body to undertake 
the new and important functions which it was proposed 
to create. The Board was reconstituted and reorganized, 
and endowed not only with the usual powers and duties 
of a State Board of Health, but with entirely new and 
peculiar functions in regard to the water supplies and 
sewerage of the towns and cities of the commonwealth. 
The board was to become the expert sanitary adviser of 
the towns, and a fortiori of the legislature, in these particu- 
lars ; and it was to be liberally supported. As a special 
recognition of the new functions, Mr. Hiram F. Mills, of 
Lawrence, perhaps the most distinguished hydraulic engi- 
neer within the state, was made a member of the reorganized 
Board, and immediately took charge of the experiments 
upon intermittent nitration. 

1 Massachusetts Drainage Commission Report (full reference given above), 
p. lxi. Boston, 1886. 



PROTECTION OF PURITY OF INLAND WATERS 141 

The statute which provided the new functions for the 
Board was approved on June 9, 1886, and was entitled 
" An Act to protect the Purity of Inland Waters." In sub- 
stance, and to a large extent in form, it corresponds with 
one recommended by the Drainage Commission. It has 
proved to be one of the most novel and satisfactory enact- 
ments for the benefit of the public health ever undertaken 
in America. In one important respect the statute actually 
adopted differed from that recommended, namely, in pro- 
viding that the members of the Board should serve without 
pay. The special functions of the State Board of Health 
as laid down in this statue, concisely stated, were as fol- 
lows : — 

1. To have the general care and oversight of all the 
inland waters of the commonwealth. 

2. To recommend legislation and suitable plans for 
systems of main sewers for the state. 

3. To cause examinations of the waters of ponds and 
streams to be made. 

4. To recommend measures to prevent the pollution of 
waters. 

5. To conduct experiments on the purification of drain- 
age. 

6. To conduct experiments on the disposal of manu- 
facturing refuse. 

7. To consult with and advise the authorities of cities 
and towns, or with others, with reference to water supply 
and drainage. 

8. To consult with and advise manufacturers with refer- 
ence to the disposal of manufacturing refuse. 

9. To bring to the notice of the attorney general all 
omissions to comply with existing laws. 

The act further provides that authorities of cities and 
towns, and all others intending to introduce systems of 
water supply or sewerage, shall submit to the Board out- 
lines of their proposed plans or schemes in relation to 



142 ON SEWAGE AND ITS PURIFICATION 

these subjects ; and that manufacturers intending to en- 
gage in any business, drainage or refuse from which may 
tend to cause the pollution of any inland waters, shall also 
give notice to the Board of their intentions. The Board 
immediately proceeded to carry out the provisions of the 
act, and in its first report, dated January, 1887, it states 
in extenso precisely what it proposes to do if adequately 
supported, and concludes : — 

"In order to make the series of examinations above out- 
lined, including monthly analyses of all waters used for 
domestic supply in the state, and biological examinations 
of certain waters injuriously affected by animal life, to- 
gether with chemical analyses of other inland waters ; to 
conduct contemplated experiments upon the purification of 
sewage and refuse from industrial establishments ; to make 
the necessary investigations in order to advise cities, towns, 
corporations and individuals in regard to the best method 
of disposing of their sewage ; and to carry out the other 
provisions of Chapter 274, — the board estimates that the 
sum of $30,000 [for the first year] will be required." 

§ 15. — The Lawrence Experiment Station of the State 
Board of Health of Massachusetts. 

The commonwealth cheerfully did its part, the legisla- 
ture granting the large sum asked for by the Board which 
thereupon proceeded to complete its organization for work 
along the lines indicated. It announced that it was ready 
to consult with and give advice to any Massachusetts city 
or town concerning its water supply or sewerage. At the 
same time it was distinctly held by the Board that, in order 
to give adequate and really expert advice, it must experi- 
ment and investigate. It was not to rest content with the 
scanty or imperfect knowledge of these subjects which was 
too often all that was available, or to accept without trial 
the methods or the results of scattered or local observers ; 



A SANITARY EXPERIMENT STATION 143 

but, first, to investigate for itself the actual condition of the 
various water supplies of the state by all means in its 
power, whether engineering, chemical or biological; and, 
second, after having obtained all available information at 
home and abroad, to establish an experiment station, and 
make for itself investigations upon the long vexed ques- 
tions of the purification of sewage and drinking water. 

This station, the Lawrence Experiment Station, the first 
of the kind in America, if not in the world, was located in 
a building adapted for the purpose, which had been con- 
structed upon land on the left bank of the Merrimac River, 
belonging to the Essex Company and already used at an 
earlier date by Mr. Mills for experiments in hydraulics. 



§ 16. — The Massachusetts Experiments at Lawrence 

The first problem attacked at the Lawrence Experiment 
Station was that of the best method for the disposal of 
sewage upon land. English and German experience had 
made it probable that much might be done in this direction 
in America ; but the knowledge available was very limited 
and of little or no practical value to American engineers, 
because the climates, soils, sewages, and civil and eco- 
nomic conditions of America are so different from those of 
Europe. Accordingly, in November, 1887, a series of 
careful experiments was begun, to test the purifying capac- 
ity of various soils and sands occurring in Massachusetts. 

For this purpose, a number of large wooden tubs or tanks 
built of cypress were cautiously filled with different soils, 
ranging from muck and garden loam on the one hand, 
through fine sand and coarse sand to mixed gravel stones, 
coarser materials, and pebbles on the other. The soil or 
sand to be tested was in each case supported by a stratum 
of stones and gravel, and underdrained through an effluent 
pipe which emptied into a large measuring basin. The 
sewage was also measured as it flowed on at the top, and 



144 0N SEWAGE AND ITS PURIFICATION 

the whole experiment was under control in every respect. 
Each tank, or " filter," was sixteen feet in diameter, or one 
two-hundredth of an acre in area, and the filtering material 
in each case was five feet in depth. The sewage to be ex- 
perimented with was drawn from one of the main sewers 
of the city of Lawrence, and was ordinary domestic city 
sewage, free from manufacturing wastes. No experiments 
of this kind had ever before been undertaken on such a 
scale or with so much care. For the first time in the his- 
tory of science, engineers, chemists and biologists worked 
together under the direction of a master in hydraulics, 
toward one common end, — the promotion of the public 
health. 

The results crowned the endeavor. Intelligent by-stand- 
ers, who saw the sewage flowing upon the filters, at the out- 
set unhesitatingly predicted failure. They felt certain, and 
did not hesitate to express their belief, that in a fortnight, at 
the latest, the filters would become clogged and foul, and the 
whole neighborhood pestilential. They did not know that 
Berlin, the German capital, disposes of all its sewage upon 
land. They forgot that the farmer once a year, or oftener, 
manures his fields with filth, and that the hungry earth re- 
ceives the gift with open mouth, devours it, and soon cries 
out for more. As soon as a few days had passed, and the 
filters had become established, the effluent began to grow 
bright and clear. Chemical analyses showed that the 
out-put was now purified sewage, comparatively free from 
odor, and poor in organic matters. Bacterial analyses 
showed that while earlier, as sewage, it was swarming with 
the germs of putrefaction and decay, it now contained only 
a few bacteria. Further studies revealed the fact that 
the foulness of the sewage was not held back as by a 
strainer ; but rather that as wood by a slow fire is turned to 
ashes, the organic matters here were slowly reduced to min- 
eral substances. No disagreeable odor developed, and the 
filters showed no signs of clogging. Thus the very name 



THE MASSACHUSETTS EXPERIMENTS 145 

"filter" became a misnomer. The by-standers were 
amazed, and could not repress their feelings of surprise and 
admiration. 



§ 17. — Anatomy and Physiology of Intermittent Filters 

Meanwhile the data of the experiments were accumulat- 
ing. Winter came on, and still the " filters " did their 
work. Already it was proved that land-disposal of sewage 
was possible for America. But, curiously enough, those 
soils — such as muck and garden loam — which many had 
predicted would be the most useful, proved to be the least 
effective. They were too close in texture, too fine, too im- 
pervious ; while sand (such as ordinary mortar sand) or 
even fine gravel proved to be the most effective. And, on 
looking into the reason why, it was soon perceived that the 
whole process is a vital one. The soils are not mere 
strainers, for at the very outset they fail to work. They are 
rather like the living sponge, — an animal whose body is 
everywhere channelled with fine passages lined with living 
cells. The fine passages in the body of the filters are 
the spaces between the sand grains; the living cells are 
the micro-organisms which, after a few days, come to dwell 
upon the sand grains and line the passages. And very much 
as the living cells of a sponge detain and destroy the or- 
ganic particles passing by them, the bacteria resident upon 
the sand grains detain and work over the organic matters 
of the sewage poured upon the filter. Again, exactly as the 
living organisms of which a sponge is essentially composed 
require oxygen to support their respiration, so those inhabit- 
ing a filter must have abundant air. This means that the 
sewage, which is usually destitute of oxygen, must not be 
applied continuously, but intermittently, so that air may 
follow it down through the filter and keep from suffoca- 
tion the purifying micro-organisms. And this also explains 
why intermittent downward filtration, under the right con- 



146 ON SEWAGE AND ITS PURIFICATION 

ditions, is always successful, while continuous nitration, or 
upward intermittent nitration, of sewage inevitably fails. 

With the main principles once established, it remained 
only to learn the details of their application. Sand proved 
better than loam, because it allowed better ventilation. 
Fine sand proved better than coarse sand, because it seems 
to be the happy mean, giving full exposure to the air by 
distributing the sewage in thin films over a vast number 
of surfaces, but yet allowing sufficient ventilation. 

The practical results were quick to follow. Once the 
purifying values of sands of particular sizes were estab- 
lished, it remained only to obtain samples of sand from any 
town desiring to dispose of its sewage on land, and to ex- 
amine and compare them with known sands, to be able to 
predict for that community either success or failure. The 
town of Framingham soon constructed a large municipal 
filter under the advice of the Board, and it has proved an 
unqualified success. The city of Brockton soon after fol- 
lowed suit, and built an admirable system of intermittent 
sand filters for the disposal of its sewage. Henceforward 
any city or town — not only in Massachusetts, but in 
America, or in the world — may, if its soil be right, and 
other conditions favorable, adopt, with perfect confidence, 
systems for the land-disposal of sewage. 

§ 18. — Theoretical Aspects of Intermittent Filtration 

Enough has now been said to make it clear that inter- 
mittent filtration is not really filtration at all, in the etymo- 
logical sense, but rather a biological and chemical process 
of extreme delicacy. A field of sandy soil may, it is true, 
be a very effective strainer ; but if worked intermittently, 
it is much more than this. A mere strainer soon chokes, 
and must be cleaned; but an intermittent filter does not 
readily choke, and is largely self-cleaning. This is a phe- 
nomenon which can be actually witnessed. When sewage 



THEORY OF INTERMITTENT FILTRATION 147 

began to be applied to the several tanks outside the Law- 
rence Experiment Station, even the most intelligent of the 
workmen predicted that the filters would soon choke and 
become a nuisance ; but after two years of actual operation, 
hardly anything more remarkable or objectionable could be 
seen upon them than upon other fertile land. This simple 
ocular demonstration was confirmed by the results of analy- 
sis, and the mechanical theory is readily disproved by a com- 
parison of the chemical composition of the effluent with that 
of the affluent. In the life-history of an intermittent filter 
there is usually a period at the outset when there is but 
little, if anything, more than a mechanical purification ; but 
under the best conditions there speedily begins a change of 
the profoundest significance. The dissolved organic mat- 
ters no longer pass out as they came in ; the suspended 
matters for the most part cease to accumulate ; and both 
appear in the effluent under other forms. Obviously, me- 
chanical processes alone could not effect such changes; 
and besides, these changes may occur under conditions 
which exclude entirely the purely mechanical hypothesis. 
A most striking example of this kind is to be found in the 
operation of a tank composed of small stones, the spaces 
between which are, as compared with much of the organic 
matter of sewage, of infinitely large size ; yet the changes 
wrought by this filter are far more extensive, and the purifi- 
cation is far more complete, than in filters of peat or garden 
soil, which are mechanically nearly perfect strainers. It 
would be hard to find a better example of the possibilities 
of sewage filtration than such a tank supplies; yet this 
filter testifies in the clearest manner to the absolute insig- 
nificance of any merely mechanical factor in the purifica- 
tion of sewage by intermittent filtration. 

§ 19. — Intermittent Filtration a Biological Process 

A theory much more reasonable than the mechanical 
hypothesis is that the action of an intermittent filter is 



148 ON SEWAGE AND ITS PURIFICATION 

fundamentally chemical. Of the powers of intermittent 
niters to effect chemical changes there is no question, as 
the previous pages of this chapter abundantly testify. 
Moreover, the transformations effected are so thorough 
that the analogy of purification by fire must occur to every 
thoughtful observer. Very early, however, the existence of 
an additional factor began to be recognized. Thus the 
Rivers Pollution Commission in their experiments on inter- 
mittent nitration, although insisting upon the chemical 
character of the purification obtained, referred to the pro- 
cess as an act of respiration, adding, most unconsciously, 
the vital to the purely chemical idea : " From all of these 
experiments, then, it appears that the action of the filter 
must not be considered as merely mechanical. The process 
carried on in it is also chemical. ... A field of porous 
soil irrigated intermittently, virtually performs an act of 
respiration." (Cf. p. 150.) 

It has since been definitely established, moreover, that 
micro-organisms are an indispensable element in the con- 
stitution of a successful intermittent filter, so that the 
essentially chemical theory has given place to one essen- 
tially vital, or biological. 

" Upon the biological theory, an intermittent filter is no 
longer regarded as a mechanical strainer, nor is it merely a 
chemical furnace ; it resembles a living organism." * 

§ 20. — Objections to Intermittent Filtration 

The Rivers Pollution Commissioners' a priori criticisms 
of the practical value of intermittent filtration are worthy 
of note as we bring this section to a close : — 

" Nevertheless there are three formidable objections to the general 
adoption of this process : first, it is entirely unremunerative. the amount 
of sewage applied to a given acre of land being probably in such a case 

1 Experimental Investigations by the State Board of Health of Massachusetts 
upon the Purification of Sewage by Filtration, etc. p. 86 1. Boston, 1890. 



INTERMITTENT FILTRATION NOT REMUNERATIVE 149 

too great to permit of the growth of any ordinary agricultural crop ; 
second, the whole of the manure ingredients of the sewage would be 
absolutely wasted ; and third, the collection of solid faecal matters upon 
the surface of the soil, with no vegetation to make use of them, would 
probably give rise to a formidable nuisance, especially in hot weather. 
We also entertain doubts as to the process being equally successful under 
ordinary management on a large scale, since the sewage would be likely 
to pass through the land in an unequal manner — in some places reach- 
ing the drains very rapidly, in others passing through the soil too 
slowly. . . . Filtration, properly conducted, results in the oxidation, 
and transformation of offensive organic substances in solution, as 
well as in the mere mechanical separation of the suspended solid 
matters which, when in motion, sewage conveys with it. If the process 
could be carried one step farther, and those harmless inorganic salts, 
which are carried off by the effluent water of a perfect sewage filter in 
too dilute a solution to be profitably extracted, could be converted into 
something positively useful, the remedy would be complete. We should 
have succeeded in not only abating an injurious nuisance, but in realizing 
a product which would help to refund expenses. This further step is 
possible in the great majority of cases ; and it is to the plan of using 
sewage in irrigation, as being in reality a filtration of the best kind, plus 
a conversion of its filthy contents into valuable products, that we have 
now to direct attention." — Rivers Pollution Commission of 1868, Re- 
port, Part I, p. 70. London, 1870. 

The objections here raised that the process is unremu- 
nerative and that the end products are wasted, still hold ; 
but the fear that a nuisance must result from the accumu- 
lation of matters on the surface of fields devoted to inter- 
mittent filtration, has been shown by experience to be 
groundless. We may now follow the line of thought 
laid down by the commissioners, and pass on to a con- 
sideration of sewage disposal by irrigation. 



§21. — Disposal and Purification of Sewage by Irrigation 

In the second report of the Commissioners appointed in 
1868 to inquire into the best means of preventing the pol- 
lution of rivers (" Mersey and Ribble Basins"), p. 19, sew- 
age irrigation is referred to as a process — 



150 ON SEWAGE AND ITS PURIFICATION 

"where sewage has been submitted, by means of irrigation, to the 
action of a vast mass of soil whose surface is covered with growing 
plants, which it feeds, whose depth is penetrated by their hungry roots, 
and whose whole substance provides an immense quantity of material 
efficient for sewage defalcation. . . . 

" If we except the laboratory experiments in the treatment of sewage 
in the intermittent downward nitration described in our first report . . . 
no other method of sewage defaecation approaches irrigation in the 
uniform excellence of its results. It is no doubt very desirable, in the 
interest of those towns where sewage cannot be dealt with by irrigation, 
that an experiment in intermittent downward filtration should be con- 
ducted on what may be considered a working scale, — when all those 
difficulties would arise which do not show themselves in a laboratory 
experiment, and when it would be proved whether the process can be 
conducted on the drainage water of, say, 20,000 people with the efficiency 
to which our laboratory experiments pointed, and without creating a 
nuisance. But the best result under that system would simply be the 
conversion of a polluting into a non-polluting stream. The injury done 
by town sewage would in that case disappear, but the agricultural value 
of it would be wholly lost. By using it in irrigation, on the other hand, 
the nuisance vanishes, while the fertilizing influence is retained and 
utilized." 

In the first report of the Commissioners, to which refer- 
ence has already been made in the preceding section, 
the purification of sewage by irrigation is well described 
as follows (Vol. I, p. 70) : — 

" We have still to discuss what may be called the agricultural remedy 
for the nuisance created by town sewage. In the first place, irrigation 
involves filtration. . . . But a filter, as has been already shown, is not 
a mere mechanical contrivance. It is a machine for oxidizing, and thus 
altogether transforming as well as for merely separating the filth of dirty 
water. And in this respect especially, irrigation necessarily includes 
filtration. Sewage traversing the soil undergoes a process to some 
extent analogous to that experienced by blood passing through the 
lungs in the act of breathing. A field of porous soil irrigated inter- 
mittently virtually performs an act of respiration, copying on an enor- 
mous scale the lung action of a breathing animal ; for it is alternately 
receiving and expiring air, and thus dealing as an oxidizing agent with 
the filthy fluid which is trickling through it. And a whole acre of soil 
three or four feet deep, presenting within it such an enormous lung sur- 
face, must be far superior as an oxidizer for dealing with the drainage 



SEWAGE DISPOSAL BY IRRIGATION 15 1 

of one hundred people, to any filter that could be practically worked for 
this purpose. 

"To this item in the character of both irrigation and filtration as 
chemical processes, there must be added another cleansing agency also 
of a chemical kind, in which the former has very greatly the advantage. 
We refer to the actual appetite for certain dissolved impurities in filthy 
water, which soil, whether in a tank or covering a field, owes both to 
general surface attraction and to the chemical affinities which some of 
its ingredients possess. This appetite is doubtless very limited in its 
amount, but it is directly proportional to the quantity of material exer- 
cising it. The superior capability of this kind which the soil of a field 
possesses, in comparison with that in a limited filtration tank, depends 
partly on the immensely greater quantity of cleansing material which an 
acre drained perhaps four feet deep necessarily brings to bear upon the 
filthy fluid ; but also and especially on the fact that in the former case 
this appetite is, except in winter time, always kept alive and fresh by 
the action of plant growth in constantly removing the deposited impuri- 
ties, and rebuilding them into wholesome organic structures. 

" Considered then merely as a mechanical and chemical agency for 
cleansing the drainage water of our towns, it seems plain that a sufficient 
extent and depth of porous soil to be used in irrigation, having peri- 
odical intervals of rest, during which the soil drains and becomes refilled 
with air, certainly must be the best possible strainer, oxidizer, and filter 
of water which, like the sewer water of our towns, contains nauseous 
organic impurities, both suspended and dissolved. That it is so, 
analyses of effluent waters have satisfactorily proved, as will be illus- 
trated at length hereafter. Meanwhile we have further to consider the 
last great advantage of the soil over all other filters, in that it utilizes a 
considerable proportion of the substances which they only separate, or 
at best transform. 

"This is the second point in our discussion of the agricultural 
remedy for river pollution, so far as that is due to the influx of town 
sewage. Sewage filth is ' fertilizing matter,' and therefore valuable as 
a manure. Every one is familiar with the idea that the fertility of a 
farm depends very much on the quantity of the live stock kept upon it. 
It is, in fact, an established maxim in agriculture that, apart from the 
use of imported and manufactured fertilizers, the maintenance of fertility 
depends very much upon the live stock which the farmer keeps upon 
the land, and the quantity of manure which he can thus apply to 
it 

"The process of filtration through sand, gravel, chalk, or certain 
kinds of soil if properly carried out is the most effective means for the 
purification of sewage to which reference has yet been made ; indeed, 



152 ON SEWAGE AND ITS PURIFICATION 

irrigation, as now carried out, owes no inconsiderable amount of its 
success to the contemporaneous effect of the filtration of the sewage 
through the soil of the irrigated fields ; for it is precisely in those cases 
in which the sewage is absorbed and disappears in porous land, that 
we have observed, in the effluent water from drains, the most complete 
purifying effect." — First Report, Rivers Pollution Commission of 1886, 
p. 60. 

§ 22. — Sewage Farms. Objections to Sewage Disposal by 
Irrigation and Sewage Farming 

The disposal of sewage by means of irrigation naturally 
involves the establishment of sewage farms, that is, a 
special kind of farming in which a liquid fertilizer is 
supplied in abundance, sometimes in superabundance. 
Enough has already been said in the preceding sections 
to show the theoretical importance and value of sewage 
as a fertilizer. It cannot be denied that sewage possesses 
elements of large fertilizing value, and it should never be 
forgotten that it may at some time be made a far more 
powerful aid than it is to-day in increasing the food supply 
of mankind. 

On the other hand, there is good reason to believe that 
the practical value of sewage as a fertilizer falls far below 
its theoretical value, owing chiefly to its enormous dilution ; 
and that any combination of farming with sewage disposal 
is, closely examined, of doubtful economic wisdom, at least 
at present, in America. It does not by any means follow 
that, because sewage contains valuable fertilizing elements, 
it is therefore wise for every city and town having sewage 
to dispose of to undertake sewage farming. It must be 
borne in mind that the civilized world appears to have been 
everywhere, within the last decade, suffering from a period of 
agricultural depression due, no doubt, in great part, to the 
vast modern improvements in agricultural machinery, and 
especially to the wonderful modern facilities for trans- 
portation, which allow food to be carried from almost any 
point of supply or superabundance to points where it is 



SEWAGE FARMS AND SEWAGE FARMING 153 

in demand, with extraordinary speed and cheapness ; and 
probably also to the remarkable advances which have been 
made in the arts of food-preserving, by means of which the 
superabundance of one season or place which was formerly 
wasted by decay may be conserved with success indefinitely, 
or until needed either there or at some remote point of the 
earth's surface. It is hardly necessary, therefore, in a period 
of depression in agriculture, such as has lately fallen upon 
much of the civilized world, to undertake agricultural opera- 
tions at a loss, and it is not surprising that objections to 
sewage farms have already arisen in some quarters from 
farmers who are obliged to compete with sewage farming. 
There can be no doubt that a greater area of land is re- 
quired for successful sewage disposal by sewage farms, 
than by mere intermittent filtration, and it is of very dubi- 
ous wisdom, at least in the United States where land 
in the neighborhood of cities is dear, where municipal 
servants are likely to be highly paid, and where, also, agri- 
cultural produce is cheap, to undertake sewage farming 
either for economic or aesthetic reasons. Moreover, as 
has already been suggested, there are other objections 
than the purely economic. Quite recently it was found 
somewhat difficult for the city of Paris to secure the privi- 
lege of adding to the area of its sewage fields because of 
the formidable opposition of the ordinary farming interests, 
which alleged with considerable vehemence that it was diffi- 
cult for them, unprovided as they were with sewage as a 
fertilizer, to compete successfully with the sewage farms 
already in existence, upon which larger crops could be 
more cheaply produced. 

There is also the sanitary objection, the force of which 
must to some extent be admitted, that vegetables and small 
fruits grown upon sewage fields and presumably watered 
with sewage are liable to become contaminated with infec- 
tious materials. We must probably allow that lettuce, 
cabbages, radishes, strawberries and similar vegetables 



154 0N SEWAGE AND ITS PURIFICATION 

or fruits, if so watered or flooded, may possibly become 
thus contaminated. On the other hand, the testimony of 
vital statistics in towns and cities in which such vegetables 
or fruits are consumed appears to be distinctly reassuring, 
and the advocates of sewage farming assert with much 
positiveness, that little or no apprehension need be felt in 
this direction. Probably the truth is that, in some countries 
very often, and in all countries in some cases, the disposal 
of sewage by irrigation is the most suitable method to be 
employed or recommended ; but that in America, at least 
for the present, for the reasons stated above, or for other 
reasons peculiar to each locality, if land treatment of any 
kind is desirable or necessary, intermittent filtration is pref- 
erable. 

§ 23. — The Partial Purification of Sewage by Chemical 
Precipitation 

In the first report of the Commissioners appointed in 
1868 to inquire into the best means of the preventing the 
pollution of rivers (" Mersey and Ribble Basins "), Vol. I, 
p. 51, 1870, the Commissioners introduce their discussion 
of this subject as follows : — 

" The cleansing of sewage has engaged the attention of many chem- 
ists and others during the past ten or fifteen years ; and various plans, 
some exhibiting great merit and ingenuity, have been proposed for 
dealing with the offensive liquid. . . . The valuable constituents of 
sewage present to the chemist a mine of wealth, which despite so many 
failures has constantly stimulated him to renewed efforts for their 
extraction in a portable and consequently marketable form. 

"The chief valuable ingredients of sewage are, 1st, the different 
forms of combined nitrogen, and 2d, phosphoric acid. The money 
value of these constituents dissolved in one hundred tons of average 
sewage is about fifteen shillings, whilst the suspended matters contain 
only about two shillings 1 worth of them. 

" There is but little difficulty in extracting the suspended matters by 
filtration, but as these do not contain quite one-seventh of the total 
valuable constituents, the process, though simple, has never been re- 
munerative ; and inasmuch as it still leaves much putrescible organic 



SEWAGE DISPOSAL BY CHEMICAL PRECIPITATION 155 

matter in solution, the mere extraction of the suspended matters of 
sewage, although doubtless tending to mitigate nuisance, does not pro- 
duce any substantial diminution of the polluting quality of the liquid. 
The operations of the chemist have, therefore, been directed chiefly to 
the soluble constituents of sewage; and have had for their object 
either the precipitation in a solid form of the valuable, but offensive, 
ingredients, so as to convert them into portable manure, or, secondly, 
the rendering them inoffensive by the action of disinfectants. Although 
these operations have not been altogether unsuccessful, they have 
hitherto entirely failed in purifying average sewage to such an extent 
as to render it admissible into running water. We have formed this 
opinion both from observations of the polluting effect of such chemi- 
cally purified sewage upon the streams into which it was admitted, and 
from the amount of putrescible organic matter revealed by the chemical 
analyses of the sewage after treatment. 

" It would obviously be rash to set any bounds to the possibilities of 
chemistry. Substances may, perhaps, be hereafter discovered capable 
of combining with and rendering insoluble the filthy constituents of our 
town drainage ; but we are compelled to admit that the present re- 
sources of this science hold out no hope that the foul matters dissolved 
in sewage will be precipitated and got rid of by the application of 
chemicals to the offensive liquid. The chemical affinities of these foul 
matters are so feeble, and the matters themselves are dissolved in such 
enormous volumes of water, that their precipitation is a problem of 
extreme difficulty." — Second Report, Rivers Pollution Commission of 
1868, pp. 18, 19. London, 1870. 

These conclusions may fairly be taken as representative 
of the best expert opinion thirty years ago. In the mean- 
time all attempts to make the chemical precipitation of 
sewage a source of pecuniary profit have been unsuccess- 
ful, and the most that is hoped for to-day is to keep the 
expense of the process within tolerable bounds. On the 
other hand, the sanitary results now obtained are decidedly 
better than those reported by the Rivers Pollution Com- 
missioners in the quotations given above. 

This method of sewage disposal is much used in Eng- 
land, either alone or in combination with disposal of the 
effluent by intermittent filtration or irrigation. The efflu- 
ent is usually well clarified, and shows a removal of about 
nine-tenths of the suspended matters and one-half of the 



156 ON SEWAGE AND ITS PURIFICATION 

total organic matters. Experience has shown that such an 
effluent can safely be admitted into a stream of relatively 
large size, provided it is not to be used for drinking pur- 
poses. 

One of the most carefully conducted establishments 
for the disposal of sewage by chemical precipitation is 
that at Worcester, Mass., and the chemical examinations 
of the effluent, there constantly made, show an average 
reduction of 95 per cent of the suspended and about 53 per 
cent of the dissolved organic matters of the sewage. It is 
fair to state, however, that Worcester has been called upon 
to defend the process before the law on complaint of Mill- 
bury, a town below Worcester, on the Blackstone river into 
which the effluent from the Worcester purification plant is 
poured. Millbury has claimed that the purification of the 
effluent is inadequate, and that a nuisance which exists 
there is due to imperfect purification of the sewage of 
Worcester. On trial it appeared that there was among the 
most competent experts a great difference of opinion as to 
the sanitary efficiency of the process. 

The reader who cares to pursue the subject of chemical 
precipitation further is referred to the following : Hazen, 
" Experiments on the Chemical Precipitation Sewage," 
Massachusetts Special Report, State Board of Health, 1890, 
p. 734. Ibid., " Chemical Precipitation of Sewage at the 
World's Fair, Chicago, 1893." Massachusetts Report, 1892, 
p. 595. "Annual Reports" of H. P. Eddy, Superintend- 
ent of Sewers, City of Worcester, Mass. Baker and Raf- 
ter, " Sewage Disposal in the United States." (D. Van 
Nostrand Co.), New York. 

§ 24. — Sewage Disposal and Purification by Electricity 

The extensive development of electrical appliances has 
naturally led to various proposals for the purification of 
sewage by electrical means. It can hardly be said, how- 






ELECTRICAL PURIFICATION OF SEWAGE 1 57 

ever, as yet, that any of these has attained a practical 
importance such as would entitle it to consideration. 

The principles involved in the electrical purification of 
sewage have been clearly stated, and the recent state of 
the subject ably summarized, by Professor (now President) 
Thomas M. Drown, 1 of Lehigh University, chemist to the 
State Board of Health of Massachusetts, in the following 
words : — 

" We may distinguish two classes of so-called electrical purification : 
first, those which electrolyze water, liberating oxygen at the positive 
pole ; and, second, those which electrolyze a solution of common salt 
and liberate chlorine in the same way. 

" The Webster process for the purification of sewage, of which a 
good deal was once heard, belonged mainly to the first class, although 
by reason of the chlorides contained in the sewage it fell also, in part, 
into the second class. The oxygen liberated at the positive pole, while 
in the nascent state, was supposed to oxidize some organic matter ; but 
as the pole was composed of iron plates, the oxygen was mainly con- 
sumed in oxidizing this iron, and the oxide of iron thus formed acted 
as a precipitating agent on the sludge in the sewage. The process was 
thus mainly one of chemical precipitation of sewage by means of oxide 
of iron, which was formed by a current of electricity passing through 
the sewage. . . . 

" The possibility of oxidizing organic matter on the large scale by 
means of nascent oxygen liberated from water by the electric current 
will, probably, never be more than a dream. Attractive as the process 
seems, the necessary conditions for accomplishing it could probably 
never be realized on a city's water supply, or on its sewage. . . . 

" The more recent systems of purification of water and sewage by 
electricity belong in the second class, that is, the decomposition by 
electrolysis of a solution of common salt. . . . 

" The principal product, under ordinary conditions, is sodium hypo- 
chlorite. . . . 

"This, then, sodium hypochlorite, is the substance with which we 
have to deal in the method of electrical purification which depends 1 on 
the electrolysis of a solution of salt or sea water. When the current of 
electricity has, in the manner above described, formed a sufficiently 
concentrated solution of sodium hypochlorite, this solution is mixed 
with the water or sewage to be purified. . . . 

1 Journal New England Water Works Association, VIII (1894), pp. 183— 
188. " On the Electrical Purification of Water [and Sewage]." 



158 ON SEWAGE AND ITS PURIFICATION 

" The so-called ' electrical ' purification of water by treating it with 
an electrolyzed solution of salt is thus seen to be simply a process of 
disinfection by sodium hypochlorite ; electricity, as such, has nothing 
to do with it. . . . 

" Ozone is generally supposed to cover a multitude of sins of pollu- 
tion, and quickly to destroy them ; but we do not know much, if any- 
thing, about its germicidal power ; and there is certainly no good reason 
for attributing any of the disinfecting action of an electrolyzed salt solu- 
tion to ozone, even did we certainly know it to be present. 

" It is unfortunate that the advocates of this system of purification of 
water and sewage are not content to attribute the purifying action of the 
electrolyzed solution of salt solely to the hypochlorite formed. There 
is nothing gained by calling it ' electrozone,' or an ' electro-saline solu- 
tion,' for there is nothing mysterious about its action, as these terms 
would lead one to suppose. Nor is it proper to speak of this system of 
purification as in any sense an ' electrical ' one. If one were to pur- 
chase two bottles of sodium hypochlorite of identically the same com- 
position, one prepared by a chemical process and the other by the 
electrolysis of a salt solution, he would not expect to find them called 
by different names. To call the latter an 'electrical disinfectant' 
would be simply fantastic." 

§ 25. — Sewage Disposal and Partial Purification by Means 
of Fermentation or Putrefaction 

A recent and interesting development in the theory and 
practice of sewage disposal and purification is that known 
as the septic process, in which advantage is taken of the 
fact that sewage is a highly putrescible fluid richly charged 
with putrefactive bacteria, in order to decompose it by its 
own ordinary processes of bacterial fermentation or putre- 
faction, thus bringing it into a condition in which it is 
believed to be more readily nitrified when, subsequently, it 
is brought in contact with the living earth, and, in particu- 
lar, causing suspended matters (sludge) to pass partly or 
wholly into solution. 

The process consists simply in allowing ordinary town 
sewage to stagnate, ferment and putrefy in a tank or 
tanks for a somewhat longer time than usual. Under 
these circumstances, the sewage contains no free oxygen, 



SELF-PURIFICATION BY PUTREFACTION 159 

and Pasteur's original idea of fermentation as u life without 
air" is fully realized. According to the evidence of vari- 
ous observers, the organic matter is thus more thoroughly 
decomposed, and the sewage is more quickly brought into 
a condition in which it is readily nitrified when, as is the 
practice, it is afterward run through slow sand filters in 
the usual methods of intermittent filtration, or by the in- 
genious modification of intermittent filtration known as 
"contact filters " proposed by Dibdin. Further details and 
a full account of the various processes employed may be 
found in a valuable paper by Professor L. P. Kinnicutt, 
entitled "Purification of Sewage by Bacterial Methods," 
Journal New England Water Works Association, Vol. XV, 
p. 119. Boston, 1900. See also the "Annual Reports" of 
the Connecticut State Sewerage Commission, begun in 1899. 

§ 26. — Fate of the Infectious Matters in Sewage Disposal 
and Sewage Purification 

For the student of sanitary science, and from the prac- 
tical point of view, it is a question of the highest importance 
what becomes of the infectious materials in sewage when 
the latter is disposed of, or purified, by any of the various 
methods described above. 

In the case of disposal by dilution, there is reason to 
believe that much depends on the special conditions under 
which the dilution takes place. If, for example, a moder- 
ate amount of sewage is emptied into a relatively large 
body of quiet water, we may safely suppose that the infec- 
tious materials which it contains, namely, micro-organisms 
of various kinds, are for the most part unfavorably affected 
by the new environment with which they are likely to meet, 
and, under the influence of light, gravity, defective food 
supply and possibly predatory infusoria or other enemies, 
as well as unfavorable temperatures, gradually perish at 
a point not very distant from that at which they were dis- 



160 ON SEWAGE AND ITS PURIFICATION 

charged. Indeed, it is impossible on any other hypothesis 
to explain the facts which have been observed in cases like 
those of Burlington, Cleveland, Chicago, Milwaukee, etc. 

It is quite otherwise, however, with those cases of puri- 
fication by dilution, in which the sewage forms a relatively 
large part of the body of the water into which it is emptied, 
and especially in those cases in which it is carried swiftly 
by running streams or currents within a short time to points 
comparatively remote from the place of disposal. In these 
cases, the same forces — light, gravity, temperature and, 
in general, unfavorable environment — would be operative, 
but yet the practical outcome might be that these were 
less availing, while the want of one other important ele- 
ment, time, would be favorable to the persistence of vitality 
of the micro-organisms which might therefore arrive, in a 
state of dilution to be sure, but yet, at comparatively remote 
points, quickly and therefore alive and virulent. It is for 
this reason that we are forced to conclude, contrary to the 
opinions held only a few years since, that quiet water, and 
not running water, purifies itself. But to this subject we 
shall return (in Chapter IX). 

When we come to the disposal of sewage upon land, we 
find the question of the fate of infectious materials in the 
sewage entirely different. If, as is always assumed, the sew- 
age to be purified is passed through, and not merely over, the 
earth, the micro-organisms which it contains are held back 
more or less completely, along with other suspended matters, 
by the living earth. One of the most striking phenomena of 
intermittent filtration which, as we have shown, is the 
fundamental process in all land treatment of sewage, is the 
disappearance of the very numerous living bacteria always 
present in the crude sewage. Some of these, no doubt, are 
mechanically detained in the upper layers of the living 
earth, the jelly-like masses which exist there being espe- 
cially favorable for entanglement of their cilia. Others 
perish from lack of food, either near the surface or, more 



FATE OF ITS INFECTIOUS MATERIALS l6l 

probably, in the lower layers of the filter, or still further 
down, in the now purified effluent which has been robbed 
of the food materials but lately abundant in it. In the 
sewage filters at the Lawrence Experiment Station it very 
early became evident that a high degree of nitrification was 
accompanied by a remarkable disappearance of bacteria, 
and repeated experiments have shown that the effluent 
from a good sewage filter is incapable of supporting any 
considerable population of bacteria. There is no doubt 
that under certain circumstances bacteria applied to the sur- 
face of an intermittent filter may live to find their way into 
the effluent, as was proved for the first time at the Law- 
rence Experiment Station by experiments made in 1888 
and published in 1890. 1 The same thing was shown a little 
later by the experiments of Fraenkel and Piefke, 2 and the 
fact is now generally accepted. 

On the other hand, it is the universal testimony of those 
familiar with intermittent filters and sewage farms that the 
ordinary effluent waters derived from well-regulated filters 
may be, and often are, drunk with impunity. We do not 
know how small a number of pathogenic bacteria may under 
certain circumstances produce disease. But there is good 
reason to think that the danger of infection in any particu- 
lar case depends, in part at least, upon the size of the dose, 
which would mean the number of micro-organisms intro- 
duced into the body. It is not claimed that sewage efflu- 
ents are desirable for drinking waters ; but there is very 
little doubt that the effluents from well-regulated filters or 
sewage farms may be safely introduced into streams or 
other bodies of water, even those which are later to be 
used as sources of water supply. 

1 " Experimental Investigations by the State Board of Health of Massachu- 
setts on the Purification of Sewage and Water," 1888-1890, p. 852. Boston, 
1890. 

2 Zeit. fur Hygiene > 8, 1890. See also Bertschinger, Vierteljahreschrift d. 
Naturforsch, Geselhch. in Zurich, 1889. 



1 62 ON SEWAGE AND ITS PURIFICATION 

If it be asked, what becomes of the infectious materials 
held back by the soil ? the answer is that they do not appear 
ordinarily to multiply, but rather to perish, along with the 
myriads of putrefactive bacteria which accompany them in 
the sewage. No fact is more striking in the history of the 
experimental niters at Lawrence than that these are vast 
charnel houses for bacteria. The sewage applied to the fil- 
ters contains, on the average, one or two millions of bacteria 
per cubic centimetre. The effluent drawn off at the bottom 
contains at most only hundreds or thousands, and this state 
of affairs is continuous day after day, month after month 
and year after year. And yet, at the same time, there 
appears to be a living resident population, tolerably con- 
stant in numbers, distributed through the different layers 
of the filter. In view of this and similar facts, we have 
above referred to the earth as the home of the bacteria ; 
but in view also of the enormous mortality of the bacteria 
in a sewage filter, it is equally clear that the earth may be 
no less truly their tomb ; and it appears to be here that the 
infectious micro-organisms present in the sewage find, 
fortunately, in this particular form of sewage disposal, 
their last resting-place. 

In the case of purification of sewage by chemical pre- 
cipitation, we may reasonably suppose that most of the 
infectious materials are carried down by the precipitant 
and got rid of in the sludge. In any event, however, the 
fate of the infectious materials in this case is of less im- 
portance, inasmuch as effluents from chemical precipitation 
works are not, as a rule, and cannot safely be, at least 
in America, admitted into a body of water used for drink- 
ing purposes. 

It has been urged in favor of the electrical purification 
of sewage that the infectious materials present are readily 
destroyed by the electric currents employed. But this, in 
view of various experiments touching the effect of electricity 
upon bacteria and other micro-organisms is, to say the 



SEWAGE FILTERS AS BACTERIAL TOMBS 163 

least, doubtful; and if what has been stated above in regard 
to the real nature of this method of purification is true, the 
problem here does not differ essentially from that affecting 
chemical precipitation, which has just been considered. 

As to the effect produced by the natural, fermentation or 
septic, process, especially when combined with Dibdin's con- 
tact filters, such as are in use at Exeter and Manchester, in 
England, very little is as yet known ; but it is fair to sup- 
pose that the fermenting process in the tank, in the absence 
of oxygen, as well as the nitrifying process in the filters in 
the presence of oxygen, are highly unfavorable to the con- 
tinued life, and still less to the multiplication, of infectious 
materials. We may safely predict that these processes 
will prove to be entirely satisfactory so far as the puri- 
fication of the sewage in respect to infectious matters is 
concerned. 



CHAPTER VIII 

ON WATER AS A VEHICLE OF INFECTIOUS DISEASE. THE 
POLLUTION OF PUBLIC WATER SUPPLIES. NOTABLE EPI- 
DEMICS DUE TO INFECTED DRINKING WATER 

" My reports are incessantly showing the foulness of private supplies 
while as regards public water supplies ... it has again and again been 
shown that their conveniences and advantages are countervailed by 
dangers to life on a scale of gigantic magnitude.'" — Sir John Simon, 
Ninth Report, Medical Officer of the Privy Council, p. 34. London, 
1867. 

" The events I am going to relate to you would, in the Middle Ages, 
have been ascribed to some mysterious influence or to supernatural per- 
secution. Science now enlightens us on the true cause of the evil, but 
at the same time imposes upon us the obligation to employ all the 
resources it gives us to combat the danger, which belongs to a class that 
human prudence can avoid." — Dr. Gueneau de Mussy, on lead poison- 
ing in the family of Louis Philippe from the water supply of the royal 
palace of Claremont. 

Inasmuch as sewage may contain any or all of the infec- 
tious materials from diseased animal bodies, and inasmuch, 
further, as it is a liquid readily miscible with water, — being 
itself hardly more than very dirty water, — while it is also 
produced in relatively large quantities by modern commu- 
nities, it is perhaps not to be wondered at that the germs 
of disease often find access to wells, springs, reservoirs 
and streams, from which water is destined sooner or later 
to be drawn for drinking purposes. 

§ 1. — Drinking Water as a Vehicle of Disease 

It has been shown above (Chapter V) that while infec- 
tious materials may sometimes enter the body through the 

164 



PURE VS. POLLUTED WATERS 165 

skin, the more common and the easier avenues are those of 
the alimentary, pulmonary and genito-urinary tracts. Of 
all the substances admitted into the alimentary canal, the 
most abundant, and perhaps the most trusted, is water. 
The " cup of cold water " has long stood as the symbol of 
charity ; and yet, from the sanitary point of view, there is 
little or no doubt that water is one of the most dangerous 
vehicles of disease which passes through the gates leading 
into the human body. 

Water chemically pure should, of course, contain no 
infectious materials, although it is an interesting fact that 
in laboratory experiments it is possible to introduce into 
distilled water a considerable number of pathogenic bac- 
teria without producing any effect upon the water discover- 
able by the most refined chemical analysis. Again, it is 
quite possible, in laboratory experiments, to mingle with 
a specimen of water millions of the germs of typhoid fever 
or Asiatic cholera without effecting perceptibly its bright 
and attractive appearance. With these facts in mind it 
becomes comparatively easy to understand that water may 
appear bright and attractive to the eye and be acceptable 
to the palate, while yet containing myriads of disease 
germs. It should not be forgotten, however, that what 
has been stated is true only of laboratory experiments, 
and rarely, if ever, happens or is likely to happen under 
natural conditions or on a large scale. 

Natural waters, such as those of springs and wells, brooks 
and other streams from uninhabited districts, should con- 
tain, and ordinarily do contain, no infectious materials ; and 
such waters, although they may contain mud, or various 
vegetable and even animal matters, are commonly described 
as "pure." But it is very different with natural waters 
which have been exposed to pollution, especially by sewage. 
From what has already been said it is clear that the latter 
may and frequently does contain infectious materials ; so 
that if sewage in any form finds its way into drinking 



1 66 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

waters, these are more than likely to prove a convenient 
vehicle for the conveyance of infectious materials into the 
human body. Even if sewage has been somewhat purified 
by dilution or other treatment, its presence in waters used 
for drinking properly constitutes a source of anxiety, the 
precise danger involved depending in any special case upon 
the degree of purification which they have undergone; 
and it is obvious that the determination of the degree of 
purification in any particular case of pollution may be a 
special problem taxing the best resources of the sanitarian. 

§ 2. — Diarrheal Diseases and Drinking Water 

A little reflection will show that while diseases of the 
skin, the throat, the lungs, the nose, etc., are accompanied 
by eruptions, exudations, expectorations or other discharges 
which may find their way into sewage, these are usually 
insignificant in amount in comparison with the bowel dis- 
charges. It is not surprising, therefore, to learn that 
diseases affecting the alimentary canal, and especially the 
intestine, particularly if accompanied by diarrhoea, are 
most conspicuous among the diseases conveyed by sew- 
age-polluted drinking water. It is now well established 
that certain bowel diseases, such as typhoid fever and 
Asiatic cholera, are readily conveyed by]drinking water, and 
numerous epidemics of these diseases have been traced to 
infected water supplies; but there is very little evidence of 
the conveyance of diseases of the skin, throat, lungs and 
nose by this particular vehicle. Moreover, there are certain 
members even of the group of diseases known as "diar- 
rhoeal" which do not seem to be as readily conveyed by drink- 
ing water as are others of the same class. Cholera infantum, 
for example, is a common, severe and often fatal diarrhosal 
disease of children. But it seems seldom, if ever, traceable 
to polluted drinking water, with which typhoid fever and 
Asiatic cholera can very often be directly connected. 



SOME DISEASES NOT WATER-BORNE 167 

§ 3. — Typhoid Fever and Asiatic Cholera 

These two diseases, and especially typhoid fever, are of 
preeminent importance and interest to the student of sani- 
tary science, and for this reason a short account of their 
natural history will be given at this point as a preface to 
further consideration of them. As long ago as 1874 expert 
opinion had concluded that " the existence of specific 
poisons capable of producing cholera and typhoid fever is 
attested by evidence so abundant and strong as to be prac- 
tically irresistible. These poisons are contained in the 
discharges from the bowels of persons suffering from these 
diseases." — Rivers Pollution Commission of 1868 , Sixth 
Report, p. 427. London, 1874. 

Typhoid fever is so called because it resembles, and was 
not formerly distinguishable from, typhus fever, otherwise 
known as "ship," "jail" or "spotted" fever. It is char- 
acterized by slow and insidious onset during a period lasting 
for about two weeks, and known as the " prodromal " period, 
during which the patient generally suffers from severe 
frontal headache, often having in addition backache, nose- 
bleed, diarrhoea and a general loss of strength which finally, 
in severe cases, compels him to take to his bed. By this 
time active fever is well established, the temperature rang- 
ing from ioo° to 105 or even higher, and characterized by 
a daily rise in the evening and a fall in the morning. 
During the period of active sickness, which usually lasts 
from four to eight weeks, delirium sometimes occurs, and 
other serious symptoms make their appearance. It is a 
characteristic of the disease, and one which distinguishes it 
from typhus fever, that in typhoid fever the small intestine 
undergoes more or less extensive and dangerous ulcerations ; 
and inasmuch as these ulcers burrow into the wall of the 
intestinal tube, they may either perforate it, allowing faecal 
matters to enter the peritoneal cavity, and causing speedy 
death from septicaemia, or they may involve important blood 






168 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

vessels, which becoming disintegrated cause profuse 
hemorrhages, often likewise followed by speedy death. 

Owing to the fact that the lower animals are not, so far 
as known, susceptible to typhoid fever, it has never been 
possible, as yet, to establish with absolute certainty the iden- 
tity of the specific germ of typhoid fever. At the same 
time there is a very general agreement that the so-called 
Koch-Eberth-Gaffky bacillus is, in all probability, the real 
and specific cause of the disease. The commonly accepted 
theory of the causation of typhoid fever is, that the specific 
bacilli, making their way into the alimentary canal in such 
vehicles as water, milk, dirt or dust, survive the journey 
through the stomach, and finding themselves in the intes- 
tine, there multiply and produce their own specific toxin, 
to the absorption of which are due the earlier symptoms 
of the disease. Simultaneously, or possibly subsequently, 
and presumably under the action of the same toxin, the 
guardian membranes of the alimentary tract are weakened 
or otherwise damaged, so that their usual resistance is 
somewhat enfeebled, and the bacilli make their way through 
them into the tissues of the body proper. Of all the tis- 
sues the spleen seems to be particularly affected ; and it 
is from this organ that those bacilli are most easily recov- 
ered which are believed to be specific and characteristic of 
the disease. 

If these commonly accepted ideas are correct, it is 
obvious that the bowel discharges of typhoid fever 
patients must naturally contain large numbers of the 
germs of typhoid fever; and that if these discharges find 
their way into sewage, such sewage must be not only pol- 
luted with the ordinary bowel discharges, but also actually 
infected with the specific germs of the disease. Further- 
more, if this sewage happens to find its way into a water 
supply that supply is liable to become a vehicle of disease 
unless it shall somehow have been purified before it is used 
for drinking purposes. It should also be observed in pass- 



TYPHOID FEVER AND ASIATIC CHOLERA 169 

ing that the journey from one human intestine to another 
may, conceivably at least, be very short, very direct and 
very quick ; and it is also easy to understand that the 
virulence of the germs may well depend upon various 
conditions to which they have been submitted en route. 

Asiatic cholera is a disease in many respects similar to 
typhoid fever, but more violent, more rapid and more 
fatal. In this case, also, owing to the insusceptibility of 
the lower animals to the disease, it has been thus far 
impossible to prove absolutely that the Spirillum, or 
Vibrio, generally regarded as the cause of the disease, 
is surely such. Certain experiments, voluntarily made 
by human beings, and a large amount of circumstantial 
evidence, have made it, however, highly probable that the 
general belief that we know the real germ of this dis- 
ease is correct. (Cf. p. 98.) 

In this case, also, it is held that the germs having been 
taken into the alimentary canal with food or drink or, pos- 
sibly, air, survive the journey through the stomach, and, 
arriving in the intestine, there multiply enormously, pro- 
ducing at the same time their specific toxin, which, in 
cholera, is far more active and far more poisonous than 
that of typhoid fever. The toxin, being absorbed into the 
body proper, is supposed to cause those profound disturb- 
ances of the organism, and often even its rapid destruc- 
tion, which are so characteristic of the disease. 

In the case of typhoid fever it was until recently very 
difficult to demonstrate with certainty the presence of 
typhoid fever bacilli in the bowel discharges of patients 
suffering from that disease, so that we were actually in 
the humiliating position of attributing to these discharges 
the principal agency in the distribution of typhoid fever, 
while yet we were quite unable satisfactorily to prove 
the presence of the germs in the discharges. From this 
unfortunate dilemma we seem to have been relieved by 
the Widal serum test, so that at present it is held to be 






170 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

easy to make the demonstration so desirable. In the case 
of Asiatic cholera, on the other hand, the number of 
micro-organisms present in the bowel discharges is so enor- 
mous that it has been from the start easy to dem- 
onstrate their existence; and there is no difficulty in 
understanding how it is that the bowel discharges of a 
single patient suffering from this disease may not only 
pollute, but also specifically infect, a particular specimen 
of sewage, with which, in turn, infection may pass into 
a water supply and, under certain conditions, arrive in the 
alimentary canal of a person drinking the infected water. 
Here, also, it is easy to follow the infection from one intes- 
tine to another, and, as in the case of typhoid fever, the 
extent and virulence of the infection will obviously depend 
upon a number of conditions en route, such as time, 
temperature, food supply, gravity, light and mechanical 
obstructions. 

§ 4. — An Epidemic of Asiatic Cholera traced to a Well. 
The Case of the Broad Street {London) Pump 

One of the earliest, one of the most famous, and one 
of the most instructive cases of the conveyance of disease 
by polluted water is that commonly known as the epidemic 
of Asiatic cholera connected with a Broad Street (Lon- 
don) well, which occurred in 1854. For its conspicuously 
circumscribed character, its violence and fatality, and espe- 
cially for the remarkable skill, thoroughness and success 
with which it was investigated, it will long remain one of 
the classical instances of the terrible efficiency of polluted 
water as a vehicle of disease. As a monument of sanitary 
research, of medical and engineering interest and of pene- 
trating inductive reasoning, it deserves the most careful 
study. No apology, therefore, need be made for giving 
of it here a somewhat extended account. 1 

1 The complete original report is entitled " Report on the Cholera Out- 
break in the Parish of St. James, Westminster, during the Autumn of 1854. 



DRINKING WATER AND ASIATIC CHOLERA 171 

(a) — The Parish of St. James \ Westminster, in 1854 

The parish of St. James, Westminster (London), occu- 
pied in 1854, 164 acres, and contained in 185 1, 36,406 
inhabitants. It was divided into three subdistricts, viz., 
those of St. James's Square, Golden Square, and Berwick 
Street. As will be seen by the map (at p. 174), it was 
situated near a part of London now well known to travel- 
lers, not far from the junction of Regent and Oxford 
streets. It was bounded by May Fair and Hanover Square 
on the west, by All Souls and Marylebone on the north, 
St. Anne's and Soho on the east and Charing Cross and 
St. Martin's-in-the-Fields on the east and south. 

In the cholera epidemics of 1832, 1 848-1 849, and 1853, 
St. James's Parish suffered somewhat but, on the aver- 
age, decidedly less than London as a whole. In 1854, how- 
ever, the reverse was the case. The Inquiry Committee 
estimated that in this year " the fatal attacks in St. James's 
Parish were probably not less than 700," and from this 
estimate computed a cholera death-rate, during 17 weeks 
under consideration, of 220 per 10,000 living in the parish, 
which was far above the highest in any other district. In 
the adjoining subdistrict of Hanover Square the ratio was 
9; and in the Charing Cross district of St. Martin's-in-the- 
Fields (including a hospital) it was 33. In 1848- 1849 the 
cholera mortality in St. James's Parish had been only 1 5 
per 10,000 inhabitants. 

(b) — The Search for the Source of the Epidemic 

Within the parish itself the disease in 1854 was very 
unequally distributed. In the St. James's Square district 
the cholera mortality was only 16 per 10,000, while in the 
Golden Square district it was 217, and in the Berwick 

Presented to the Vestry by the Cholera Inquiry Committee, July, 1855." 
London, J. Churchill, 1855. 



172 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

Street district, 212. It was plain that there had been a 
special cholera area, a localized, circumscribed district. 
This was eventually minutely studied in the most pains- 
taking fashion as to population, industries, previous sani- 
tary history, meteorological conditions and other general 
phenomena common to London as a whole; with the 
result that it was found to have shared with the rest of 
London " a previous long-continued absence of rain . . . ; 
a high state of temperature both of the air and of the 
Thames . . . ; an unusual stagnation of the lower strata 
of the atmosphere, highly favorable to its acquisition of 
impurity . . . ; and although it was impossible ... to fix 
the precise share which each of the conditions enumerated 
might separately have had in favoring the spread of 
cholera, the whole history of that malady, as well as of 
the epidemic of 1854, and indeed of the plagues of past 
epochs, justifies the supposition that their combined opera- 
tion, either by favoring a general impurity in the air or in 
some other way, concurred in a decided manner, last sum- 
mer and autumn (1854), to give temporary activity to the 
special cause of that disease." (Report of Cholera Inquiry 
Committee, pp. 38, 39.) The Inquiry Committee did not, 
however, rest satisfied with these vague speculations and 
conclusions. "... But, as previously shown in the history 
of this local outbreak, the resulting mortality was so dispro- 
portioned to that in the rest of the metropolis, and more 
particularly to that in the immediately surrounding dis- 
tricts, that we must seek more narrowly and locally for 
some peculiar conditions which may help to explain this 
serious visitation." 

Accordingly, special inquiries were made within the dis- 
trict involved in regard to its "elevation of site"; "soil 
and subsoil" (including an extended inquiry into the his- 
tory of a " pest-field," said to have been located within this 
area in 1665-1666, to which some had attributed the cholera 
of 1854); "surface and ground plan"; "streets and 



ASIATIC CHOLERA AND THE BROAD ST. PUMP 1 73 

courts"; " density of population"; "character of the 
population"; "dwelling houses — internal economy as to 
space, light, ventilation and general cleanliness"; "dust- 
bins and accumulations in yards, cellars and areas " ; 
" cesspools, closets and house-drains " ; " sewers, their 
waterflow and atmospheric connection " ; " public water 
supply " ; and " well-water supply." No peculiar condi- 
tion or adequate explanation of the origin of the epidemic 
was discovered in any of these, even after the most search- 
ing inquiry, except in the well-water supply. Abundant 
general defects were found in the other sanitary factors, 
but nothing peculiar to the cholera area, or, if peculiar, 
common to those attacked by the disease, could be found 
excepting the supply of well water. 

(c) — Suspicion falls upon the Broad Street Pump. The 
Investigations of Dr. John Snow. 

At the very beginning of the outbreak, Dr. John Snow, 
with commendable energy, had taken the trouble to get 
the number and location of the fatal cases, as is stated in 
his own report (Report of Cholera Inquiry Committee, pp. 
100 et sea.): — 

" I requested permission, on the 5th of September, to 
take a list, at the General Register Office, of the deaths 
from cholera registered during the week ending the 2d of 
September in the subdistricts of Golden Square and Ber- 
wick Street, St. James's, and St. Anne's, Soho, which was 
kindly granted. Eighty-nine (89) deaths from cholera were 
registered during the week in the three subdistricts. Of 
these only six (6) occurred on the first four days of the 
week; four (4) occurred on Thursday, August 31; and 
the remaining 79 on Friday and Saturday. I considered, 
therefore, that the outbreak commenced on the Thursday ; 
and I made inquiry in detail respecting the 83 deaths 
registered as having taken place during the last three days 
of the week. 



174 WATER AS A VEHICLE OF INFECTIOUS DISEASE 



" On proceeding to the spot I found that nearly all the 
deaths had taken place within a short distance of the pump 
in Broad Street. There were only ten (10) deaths in 
houses situated decidedly nearer to another street pump. 
In five (5) of these cases the families of the deceased 
persons told me that they always sent to the pump in 
Broad Street, as they preferred the water to that of the 
pump which was nearer. In three other cases, the de- 
ceased were children who went to school near the pump 
in Broad Street. Two of them were known to have drunk 
the water, and the parents of the third think it probable 
that it did so. The other two deaths beyond the district 
which the pump supplies represent only the amount of 
mortality from cholera that was occurring before the 
eruption took place. 

" With regard to the 73 deaths occurring in the locality 
belonging, as it were, to the pump, there were 61 instances 
in which I was informed that the deceased persons used 
to drink the water from the pump in Broad Street, either 
constantly or occasionally. In six (6) instances I could 
get no information, owing to the death or the departure of 
every one connected with the deceased individuals ; and in 
six (6) cases I was informed that the deceased persons did 
not drink the pump water before their illness. 

" The result of the inquiry consequently was that there 
had been no particular outbreak or increase of cholera in 
this part of London, except among the persons who were 
in the habit of drinking the water of the above-mentioned 
pump well. 

" I had an interview with the Board of Guardians of 
St. James's Parish on the evening of Thursday, 7th of Sep- 
tember, and represented the above circumstances to them. 
In consequence of what I said the handle of the pump was 
removed on the following day. . . . 

" The additional facts that I have been able to ascertain 
are in accordance with those above related ; and as regards 



ASIATIC CHOLERA AND THE BROAD ST. PUMP 175 

the small number of those attacked who were believed not 
to have drunk the water from the Broad Street pump, it 
must be obvious that there are various ways in which the 
deceased persons may have taken it without the knowl- 
edge of their friends. The water was used for mixing 
with spirits in some of the public houses around. It was 
used likewise at dining rooms and coffee-shops. The 
keeper of a coffee-shop which was frequented by me- 
chanics, and where the pump water was supplied at dinner 
time, informed me on the 6th of September that she was 
already aware of nine of her customers who were dead." 

On the other hand, Dr. Snow discovered that while a 
workhouse (almshouse) in Poland Street was three-fourths 
surrounded by houses in which cholera deaths occurred, 
out of 535 inmates of the workhouse only five (5) cholera 
deaths occurred. The workhouse, however, had a well of 
its own in addition to the city supply, and never sent for 
water to the Broad Street pump. If the cholera mortality 
in the workhouse had been equal to that in its immediate 
vicinity, it should have had fifty deaths. 

A brewery in Broad Street employing seventy workmen 
was entirely exempt, but having a well of its own, and 
allowances of malt liquor having been customarily made 
to the employees, it appeared likely that the proprietor was 
right in his belief that resort was never had to the Broad 
Street well. 

It was quite otherwise in a cartridge factory at No. 38 
Broad Street, where about two hundred work-people were 
employed, two tubs of drinking water having been kept 
on the premises and always filled from the Broad Street 
well. Among these employees eighteen died of cholera. 
Similar facts were elicited for other factories on the same 
street, all tending to show that in general those who drank 
the water from the Broad Street well suffered either from 
cholera or diarrhoea, while those who did not drink that 
water escaped. The whole chain of evidence was made 



176 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

absolutely conclusive by several remarkable and striking 
cases like the following : — 

"A gentleman in delicate health was sent for from 
Brighton to see his brother at No. 6 Poland Street, who 
was attacked with cholera and died in twelve hours, on 
the 1st of September. The gentleman arrived after his 
brother's death, and did not see the body. He only 
stayed about twenty minutes in the house, where he took 
a hasty and scanty luncheon of rump steak, taking with 
it a small tumbler of cold brandy-and-water, the water 
being from Broad Street pump. He went to Pentonville, 
and was attacked with cholera on the evening of the fol- 
lowing day, September the 2d, and died the next evening." 

" The deaths of Mrs. E and her niece, who drank 

the water from Broad Street at the West End, Hampstead, 
deserve especially to be noticed. I was informed by Mrs. 
E 's son that his mother had not been in the neighbor- 
hood of Broad Street for many months. A cart went from 
Broad Street to West End every day, and it was the cus- 
tom to take out a large bottle of the water from the pump 
in Broad Street, as she preferred it. The water was taken 
out on Thursday, the 31st of August, and she drank of it 
in the evening and also on Friday. She was seized with 
cholera on the evening of the latter day, and died on Sat- 
urday. A niece who was on a visit to this lady also drank 
of the water; she returned to her residence, a high and 
healthy part of Islington, was attacked with cholera, and 
died also. There was no cholera at this time, either at 
West End or in the neighborhood where the niece died. 
Besides these two persons only one servant partook of the 
water at West End, Hampstead, and she did not suffer, or, 
at least, not severely. She had diarrhoea." 

Dr. Snow's inquiry into the cases of cholera which were 
nearer other pumps showed that in most the victims had 
preferred, or had access to, the water of the Broad Street 
well, and in only a few cases was it impossible to trace 



ASIATIC CHOLERA AND THE BROAD ST. PUMP 1 77 

any connection with that pump. Finally, Dr. Snow made 
a statistical statement of great value, which is here given 
in its original form. 



THE BROAD STREET (LONDON) WELL AND DEATHS FROM 
ASIATIC CHOLERA NEAR IT IN 1854 





Number 






Number 




Date 


of Fatal 
Attacks 


Deaths 


Date 


of Fatal 
Attacks 


Deaths 


August 19 . . 




, 


Sept. II . . . 


5 


15 


" 20 . . 




O 


" 12 . 






1 


6 


" 21 . . 




2 


" 13 • 






3 


13 


22 . . 


O 


O 


" 14 ■ 









6 


" 23 . . 




O 


" 15 • 






1 


8 


" 24 . . 




2 


" 16 . 






4 


6 


" 25 . . 


O 


O 


" 17 . 






2 


5 


" 26 . . 




O 


" 18 . 






3 


2 


" 27 . . 




I 


" 19 • 









3 


" 28 . . 




O 


" 20 . 












" 29 . . 




I 


" 21 . 






2 





" 30 • • 


8 


2 


" 22 . 








2 


" 31 • • 


56 


3 


" 23 . 








3 


Sept. 1 . . 


143 


70 


" 24 . 











2 . . 


116 


127 


" 25 . 











3 • • 


54 


76 


" 26 . 








2 


4 . . 


46 


71 


" 27 . 











" 5 • • 


36 


45 


" 28 . 









2 


6 . . 


20 


37 


" 29 . 












" 7 • • 


28 


32 


" 30 • 












" 8 . . 

" 9 • • 


12 
11 


30 
24 


Date unknown 




45 











10 . . 


5 


18 


Total . . 


616 


616 



(d) — The Rev. Mr. Whitehead's Detailed Studies of 
Broad Street and Its Pump 

In addition to the original and general inquiry conducted 
from the time of the outbreak by Dr. Snow, the Rev. H. 
Whitehead, M.A., 1 curate of St. Luke's in Berwick Street, 



1 "The Rev. H. Whitehead, M.A., to whom medicine is in a great 

measure indebted for that elaborate investigation of the cholera outbreak in 

the parish of St. James, Westminster (the Broad Street pump outbreak), 

which it is now known gives to Dr. Snow's opinion of its origin a probability 

N 



178 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

and like Dr. Snow, a member of the Cholera Inquiry Com- 
mittee, whose knowledge of the district both before and 
during the epidemic, owing to his official position, gave 
him unusual advantages, made a most elaborate and pains- 
taking house-to-house investigation of one of the principal 
streets affected, viz., Broad Street itself. Mr. White- 
head's report, like that of Dr. Snow, is a model of careful 
and extended observation and study, cautious generalizing 
and rigid verification. It is an excellent instance of in- 
ductive scientific inquiry by a layman in sanitation. Mr. 
Whitehead found the number of houses on Broad Street, 
49; the resident householders, 35; the total number of 
resident inhabitants, 896; the total number of deaths 
among these, 90. Deaths among non-residents (workmen, 
etc.) belonging to the street, 28. Total deaths chargeable 
to this street alone, 118. Only 10 houses out of 49 were 
free from cholera. The dates of attack of the fatal cases 
resident in this single street were as follows : — 



Date of Attack 


Number of 
Fatal Attacks 


Date of Attack 


Number of 
Fatal Attacks 


August 12 . 
" 28 . 
" 30 . 
" 31 • 

Sept. 1 . 
2 . 








I 

I 
I 
6 
26 
24 
9 


Sept. 4 

" 5 

" 6 

" 7 

" 8 

" 9 


8 
6 

5 


2 
1 


" 3 • 


90 



Mr. Whitehead's detailed investigation was not made 
until the spring of 1855, but in spite of this fact it supplied 
most interesting and important confirmatory evidence of 
Dr. Snow's theory that the Broad Street well was the source 
of the epidemic. Mr. Whitehead, moreover, went further 

practically amounting to a demonstration." — Mr. J. Netten Radcliffe, 
"On Cholera in London in 1866," Ninth Rep. Med. Officer of the Privy 
Council, p. 288. 



DRINKING WATER AND ASIATIC CHOLERA 179 

than Dr. Snow, and endeavored to find out how the well 
came to be infected, why its infectious condition was so 
limited as it appeared to have been, and to answer various 
other questions which occurred in the course of his inquiry. 
As a result, he concluded that the well must have been 
most infected on August 31 ; that for some reason unknown 
a partial purification began on September 2, and thereafter 
proceeded rapidly. There was some evidence that on Aug- 
ust 30 the water was much less infected than on the 31st, 
so that its dangerous condition was apparently temporary 
only. He further discovered that in the house No. 40 
Broad Street, which was the nearest house to the well, there 
had been not only four fatal cases of cholera contempora- 
neous with the epidemic, but certain earlier cases of an 
obscure nature, which might have been cholera, and that 
dejecta from these had been thrown without disinfection into 
a cesspool very near to the well. On his reporting these 
facts, in April, 1855, to the main committee, Mr. J. York, 
secretary and surveyor to the committee, was instructed to 
survey the locality and examine the well, cesspool and 
drains at No. 40 Broad Street. 

(e) Survey and Description of the Broad Street Well 
and its Surroundings 

Mr. York's report revealed a startling condition of af- 
fairs. The well was circular in section, 28 ft. 10 in. deep, 
6 ft. in diameter, lined with brick, and when examined con- 
tained 7 ft. 6 in. of water. It was arched in at the top, 
dome fashion, and tightly closed at a level 3 ft. 6 in. below 
the street, by a cover occupying the crest of the dome. 

The bottom of the main drain of the house No. 40 Broad 
Street lay 9 ft. 2 in. above the water level, and one of its 
sides was distant from the brick lining of the well only 2 ft. 
8 in. It was — 

"constructed on the old-fashioned plan of a flat bottom, 12 in. wide, 
with brick sides rising about 12 in. high, and covered with old stone. 



180 WATER AS A VEHICLE OF INFECTIOUS '^DISEASE 

As this drain had but a small fall, or inclination outward to the main 
sewer, the bottom was covered with an accumulation of soil deposit 
about 2 in. thick ; and upon clearing this soil away the mortar joints 
of the old stone bottom were found to be perished, as was also all the 
jointing of the brick sides, which had brought the brick work into the 
condition of a sieve, and through which the house drainage water 
must have percolated for a considerable period. . . . 

" After opening back the main drain, a cesspool intended for a trap, 
but misconstructed, was found in the area, 3 ft. 8 in. long, by 2 ft. 6 in. 
wide, and 3 ft. deep ; and upon or over a part of this cesspool a com- 
mon open privy (without water supply), for the use of the house, was 
erected, the cesspool being fully charged with soil. This privy was 
formed across the east end of the area, and upon removing the soil the 
brickwork of the cesspool was found to be in the same decayed condi- 
tion as the drain, and which may be better comprehended by stating 
that the bricks were easily lifted from their beds without any, the least, 
force ; so that any fluid could readily pass through the work, or, as was 
the case when first opened, over the top course of bricks of the trap, 
into the earth or made ground immediately under and adjoining the end 
wall eastward, this surface drainage being caused by the accumulation 
of soil in, and the misconstruction of, the cesspool. . . . 

" Thus, therefore, from the charged condition of the cesspool, the 
defective state of its brickwork, and also that of the drain, no doubt re- 
mains upon my mind that constant percolation, and for a considerable 
period, had been conveying fluid matter from the drains into the well ; 
but lest any doubt should arise upon this subject hereafter, I had two 
spaces of the brick steining, 2 ft. square each, taken out of the inside 
of the well — the first 13 ft. deep from the level of the street paving, 
the second 18 ft. deep, and a third was afterward opened still lower, 
when the washed appearance of the ground and gravel fully corroborated 
the assumption. In addition thereto, the ground was dug out between 
the cesspool and the well to 3 ft. below the bottom of the former, 
and its black, saturated, swampy condition clearly demonstrated the 
fact, as did also the small furrowed appearance of the underlying gravel 
observed from the inside of the well, from which the fine sand had been 
washed away during the process of filtration." — Report of J. York, 
Secretary a?id Surveyor to the Cholera Inquiry Coinmittee. — L. c. 

It was thus established, as clearly as can be done by 
circumstantial evidence, that the great epidemic in St. 
James' Parish, Westminster, London, in 1854, was caused 
by the polluted water of the Broad Street well, which for a 



ASIATIC CHOLERA AND THE BROAD ST. WELL l8l 

very few days was probably infected with cholera germs. 
It is much less clear how the well became infected, but it 
seems probable that the dejecta of a cholera patient found 
tolerably direct access to the well from the cesspool or 
drain of a house near by. There is no evidence whatever 
that the germs multiplied in the well, but rather much 
evidence that they rapidly died out. It is repeatedly stated 
in the report that the water was preferred for drinking 
because it was " cold," i.e. colder than the cistern water 
derived from the public water supply, and this condition 
would probably favor such dying out. 

That the water had long been polluted, there can be no 
doubt. There was evidence of this, and also some evidence 
that it was worse than usual at the time when it was prob- 
ably infected. One consumer spoke of it as having been 
at that time " offensive " in taste or odor. It is instructive 
to note that mere pollution seems to have done no obvi- 
ous harm. Specific infection, however, produced Asiatic 
cholera. 

Mr. Whitehead, in his singularly fair and candid report, 
raises an interesting question, viz., why, if an early and 
unrecognized case in the house in question brought about 
infection of the well, should not the four severer cases of 
undoubted cholera subsequently in the same house, with 
no known change in the drainage, have produced even 
greater disaster ? This question remains unanswered, ex- 
cept that after the removal of the pump handle on the 
8th of September access to the well was shut off, and 
during the intermediate week the well may have been 
avoided by the frightened people ; or, owing to illness, less 
water may have been used in No. 40 Broad Street, so 
that the cesspool did not overflow ; or some other condi- 
tion, unknown, may have been changed. 



1 82 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

§ 5. — An Epidemic of Asiatic Cholera in London in 1866 
traced to a Polluted and Infected Surface Water Supply 

Dr. John Snow, in 1854, gave it as his opinion that not 
only wells but also public water supplies of far more gen- 
eral distribution, such as those furnished by cities or cor- 
porations and derived from rivers, may, under certain 
circumstances, be carriers of cholera. The great epidemics 
of Asiatic cholera in London in 1832, 1 848-1 849 and 
1 85 3-1 8 54 had so strongly enforced this idea that in deal- 
ing with an important problem raised by epidemic cholera 
in London in 1866 Mr. J. Netten Radcliffe states that, 
" The predominant lesson derived from the outbreaks of 
1 848- 1 849 and 1 85 3-1 854 was that the localities of chief 
prevalence of the disease were mainly, if not solely, de- 
termined by the degree of impurity of the water supply." 1 

In 1866 Asiatic cholera, having again become epidemic 
in London, appeared in marked abundance in certain 
eastern districts of the city. A special investigation of 
its origin and distribution in those parts was made for the 
medical officer of the Privy Council (Mr., afterward Sir, 
John Simon), by Mr. J. Netten Radcliffe, whose very elabo- 
rate and painstaking report (published in extenso in the 
Ninth Report, London, 1867) served to fasten the blame 
for the excess in East London upon a special pollution and 
infection of a portion of the public water supply of the 
district, derived from the river Lea. 2 

Briefly stated, it may be said that the epidemic of 1866 

1 Ninth Rep. Med. Officer of the Privy Council, p. 295. See also Simon, 
Report on the Cholera Epidemics of London in 1848-1849 and 1853-1854 
as affected by the Consumption of Impure Water. London, 1856. 

2 Like some more recent students of English sanitation, Mr. Radcliffe 
seems to have been puzzled in regard to the correct spelling of this word. 
His note on the subject is therefore interesting. "The Rivers Pollution Com- 
missioners have spelled the name of this river Lee. All the standard maps 
and geographical works of reference spell the name Lea. I have adhered to 
the orthography commonly used." — Op. ciL, p. 280. 



ASIATIC CHOLERA IN LONDON IN 1866 



183 



in England began on April 28 with a case in Bristol 
imported from Rotterdam. By May 15 the disease was 
prevailing among certain emigrants on board ships in the 
Mersey bound for New York. These emigrants had re- 
cently come from infected places on the continent. Scat- 
tered cases or outbreaks soon began to be reported from 
various parts of England, such as Swansea and South- 
ampton. The first death reported in London, according 
to Mr. Simon, was on July 18, and two days later an 
alarming number of cases appeared in East London. 
By July 21 it was clear that a special epidemic was pre- 
vailing in that region, and it is this special outbreak or 
"explosion" of cholera which forms the subject of Mr. 
Radcliffe's report. During the three months, — July, 
August and September, — there were registered in all 
England 10,365 deaths from cholera and 9570 deaths 
from diarrhoea. During the seven days ending August 4 
there were in London alone 1053 deaths from cholera, and 
on one day (August 1) 204. The following comparison 
given by Mr. Radcliffe of the duration and mortality of 
the cholera epidemics in London in 1849, 1854, and 1866 
is noteworthy : — 





Epidemic 
of 


Duration 


Deaths from 
Cholera 


Ratio to 10,000 
Inhabitants 


Deaths from 
Diarrhoea 


Ratio to io,coo 
Inhabitants 


1849 

1854 
1866 


23 weeks 
23 weeks 
23 weeks 


13,565 
10,684 

5,548 


51 

43 
18 


2926 

2551 
2692 


I3.O 
IO. I 

8.8 





" Cholera having been so less fatal in proportion to the 
number of persons attacked by the disease [in 1866] . . . 
the foregoing results would indicate increased, and perhaps 
increasing, safeguards in the metropolis." — Op. cit., p. 277. 
Mr. Radcliffe's investigation soon showed, however, that 
further safeguards, at least in respect to water supply, 
were urgently needed. 



1 84 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

Of the whole number of cholera deaths (5548), 3909 oc- 
curred in the east districts — "more than double the amount 
distributed over the rest of the metropolis." Moreover, it 
was in these districts that it increased most rapidly and 
to the highest point, and that it fell off afterward most 
quickly. Again, "no relative development of like magni- 
tude, suddenness, and shortness of duration had occurred 
in previous outbreaks of cholera in the metropolis," either 
in these or other districts. The brunt of the malady in 
1849 and 1854 had fallen upon the south districts. 

" London was unquestionably less filthy at the time of 
the outbreak than in any previous outbreak. But the east 
districts could not claim a preeminence of filth. In the 
west of the metropolis and south of the river there were 
many localities as filthy. Neither Rotherhithe, nor Ber- 
mondsey, nor Southwark, nor Westminster, can be compared 
favorably with the east of London, yet the three former 
places suffered in a trifling degree as compared with the 
latter." — Op. cit., p. 293. 

Mr. Radcliffe carefully considered, in addition to "filth," 
such possible or supposed causes of cholera as "soil," 
" density of population," " sewerage," " locality," " meteor- 
ological states" and "altitude," and concluded that "not 
one of the conditions named . . . and believed to be liable 
to affect the progress and development of epidemic cholera, 
the disease being present, will account for more than very 
limited fluctuations of the outbreak, or for its localization 
in any particular spot in a restricted degree only. Any 
combination of these conditions is, moreover, equally inef- 
ficacious in explaining the peculiar localization and fluctua- 
tion in the east districts of the metropolis." 

(a) — Suspicion directed to the Public Water Supply of 
the Infected District 

The water supply alone remained to be considered, and 
" from the commencement of the localization of cholera in 



ASIATIC CHOLERA IN LONDON IN 1866 185 

the east districts the probable association of this circum- 
scription with an impure water supply was forced upon the 
mind. . . . During the week ending the 28th of July it 
became obvious that the brunt of the outbreak had fallen 
upon the east districts; and in the bill of mortality for 
the week the registrar general directed attention to the 
fact that the field of prevalence of the disease was supplied 
with water from the East London Water Company's works." 
On August 1 the water company was notified that its 
supply was under suspicion, and the local sanitary author- 
ities were recommended by Mr. Simon to issue the 
following : — 

CHOLERA. NOTICE ! 

" The inhabitants of the District within 
which Cholera is prevailing are earnestly 
advised not to drink any water which has 
not previously been boiled. ..." 

Further investigation satisfied Mr. Radcliffe that the 
"explosion" of cholera, which occurred just prior to July 
21, had its origin in a temporary and limited infection of 
one portion of the East London Company's waterworks 
situated at Old Ford, on the river Lea. This river, con- 
siderably polluted by sewage in its upper reaches, was 
subjected to subsidence and filtration above, and at, Lea 
Bridge, respectively. Some of the filtered water was dis- 
tributed from this point, and no blame was attached to this 
portion of the supply. The remainder was conveyed 
farther into the metropolis by a closed iron conduit, to two 
covered reservoirs on the west bank of the Lea at Old Ford, 
and from this point pumped into the distributing mains. 
On the east side of the river at Old Ford were two uncov- 
ered reservoirs of large capacity, one of which had, at the 
time of the outbreak, direct connection with the covered 
reservoirs of filtered water. The open reservoirs were also 



1 86 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

connected with the filtering beds at Lea Bridge by an open 
and foul conduit, and they sometimes received the waste 
water from them unfiltered. They seem to have served as 
a reserve of unfiltered water to draw upon in case of clog- 
ging of the filter beds or in case of fire. 

It was admitted that the filter beds had, in fact, been 
seriously clogged just before the cholera outbreak, and it 
was in evidence that on at least one occasion, early in 
July, some 300,000 gallons of unfiltered water had been 
drawn from one of the uncovered reservoirs into the cov- 
ered reservoirs, to make good a deficiency in filtered water 
due to clogging of the filters. Precisely how this unfil- 
tered and impure water may have become infected by 
choleraic poison is not known. Mr. Radcliffe believed 
that soakage from the river, which was known to have 
been infected in its lower reaches, probably found access 
to the open reservoir. This is certainly possible, but it 
seems more likely that the infection may have found 
direct access to the river in the unpurified sewage of some 
city or town on the upper watershed above the point of 
intake of the East London Company's works. "In its 
course it (the river Lea) drains about 570 square miles of 
country, and before reaching Enfield Lock ... it receives 
the sewage of upward of 150,000 souls. It receives in its 
course, also, as affluents, several smaller streams, each in 
its degree a recipient of sewage." — Op. cit., p. 296. 

The medical officer of the Privy Council, in his historical 
summary of the progress of the disease in England, states 
that even "within the next few days" after May 15 two 
cases were reported at Swansea, " and single cases in vari- 
ous other parts of the country." Of early July he writes, 
" evidently England was now being infected in many dif- 
ferent directions. Reports of new centres of infection 
became more and more frequent." It is not difficult to 
suppose that some one or more obscure case, or cases, may 
have occurred at this time or afterward upon the watershed 



TYPHOID FEVER IN LAUSEN, SWITZERLAND 187 

of the Lea, and thus have directly infected that river, pol- 
luted as it plainly was with unpurified sewage. 

(b) — The Obvious Value of Filtration as a Sanitary 
Safeguard 

On any hypothesis the supreme value and importance 
of filtration became manifest, for it was evidently only the 
unfiltered river water which did harm. The supply pumped 
from Lea Bridge was of filtered water derived from a highly 
polluted, and probably infected, river, and yet seems to 
have caused no spread of the disease. 

This apparently logical conclusion as to the value of fil- 
tration was, nevertheless, laid open to serious question a 
few years later, in consequence of the famous Lausen 
epidemic, to a consideration of which we may now turn. 

§ 6. — An Epidemic of Typhoid Fever in Lausen, Switzer- 
land, due to an Infected Ground Water or Spring 

Typhoid fever derived from impure drinking water is now 
recognized as of common occurrence, and a great number 
of destructive epidemics have been traced to this source. 
The first to attract universal attention was that which 
occurred in Lausen, Switzerland, in 1872; and because of 
certain peculiar conditions connected with it, and especially 
because of its influence upon the theory and practice of the 
purification of water by filtration, it deserves the most care- 
ful consideration by all students of sanitation. 

The epidemic occurred in the little village of Lausen in 
the canton of Basel in Switzerland in August, 1872. 
Lausen was a well-kept village of 90 houses and 780 
inhabitants, and had never, so far as known, suffered 
from a typhoid epidemic. For many years it had not 
had even a single case of typhoid fever, and it had 
escaped the cholera even when the surrounding country 
suffered from it. Suddenly, in August, 1872, an outbreak 



WATER AS A VEHICLE OF INFECTIOUS DISEASE 



of typhoid fever occurred, affecting a large part of the 
entire population. 

A short distance south of Lausen was a little valley, the 
Fiirlerthal, separated from Lausen by a hill, the Stockhal- 
den, and in this valley, on June 19, upon an isolated farm, 
a peasant, who had recently been away from home, fell ill 
with a very severe case of typhoid fever, which he had 
apparently contracted during his absence. In the next 
two months there occurred three other cases in the neigh- 
borhood, — a girl, and the wife and the son of the peasant. 

No one in Lausen knew anything of these cases in the 
remote and lonely valley when suddenly, on August 7, ten 
cases of typhoid fever appeared in Lausen, and by the end 
of nine days, fifty-seven cases. The number rose in the 
first four weeks to more than one hundred, and by 
the end of the epidemic in October to about 130, or 
seventeen per cent of the population. Besides these, 
fourteen children who had spent their summer vacation in 
Lausen fell ill with the same disease in Basel. The fever 
was distributed quite evenly throughout the town, with the 
exception of certain houses which derived their water from 
their own wells and not from the public water supply. 
Attention was thus fixed upon the latter, which was obtained 
from a well or spring at the foot of the Stockhalden hill on 
the Lausen side. The well was walled up, covered and ap- 
parently protected, and from it the water was conducted to 
the village, where it was distributed by several public foun- 
tains. Only six houses used their own wells, and in these six 
there was not a single case of typhoid fever, while in almost 
all the other houses of the village, which depended upon the 
public water supply, cases of the disease existed. Suspicion 
was thus directed to the water supply as the source of the 
typhoid poison, very largely because no other source could 
well be imagined. A distribution of the disease from the 
farm through the air was hardly conceivable because houses 
in the Fiirlerthal, although lying upon the same plateau and 



TYPHOID FEVER IN LAUSEN, SWITZERLAND 189 

naturally more accessible through the atmosphere, remained 
free from the disease, a fact which seemed to prove that the 
infected farmhouse could not have communicated the dis- 
ease to Lausen either through the ground water or through 
the air. 

In order, however, to clinch the evidence that the Lausen 
water supply had been infected, it became desirable to show 
some source from which an infection, so unusual and re- 
markable, could have come, and precisely how it had hap- 
pened. There had long been a belief that the Lausen well 
or spring was fed by and had a subterranean connection 
with a brook (the Furler brook) in the neighboring Fiirler 
valley ; and since this brook ran near the peasant's house 
and was known to have been freely polluted by the excreta 
of the typhoid fever patients, absolute proofs of the connec- 
tion between the well of Lausen and the Furler brook could 
not fail to be highly suggestive and important. Fortunately 
such proofs were not far to seek. Some ten years before, 
observations had been made which had showed an intimate 
connection between the brook and the well. At that time, 
without any known reason, there had suddenly appeared 
near the brook in the Furler valley below the hamlet, a hole 
about eight feet deep and three feet in diameter, at the bot- 
tom of which a considerable quantity of clear water was 
flowing. As an experiment, the water of the little Furler 
brook was at that time turned into this hole, with the result 
that it had all flowed away underground and disappeared, 
and an hour or two later the public fountains of Lausen 
which, on account of the dry weather prevailing at the time, 
were barely running, had begun flowing abundantly. The 
water from them, which was at first turbid, later became 
clear ; and they had continued to flow freely until the Furler 
brook was returned to its original bed and the hole had 
been filled up. But every year afterward, whenever the 
meadows below the site of the hole were irrigated or over- 
flowed by the waters of the brook, the Lausen fountains 



190 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

soon began to flow more freely. In the epidemic year 
(1872) the meadows had been overflowed as usual from 
the middle to the end of July, which was the very time 
when the brook had been infected by the excrements of 
the typhoid patients. The water supply of Lausen had in- 
creased as usual, had been turbid at the beginning and 
had had a disagreeable taste. And about three weeks 
after the beginning of the irrigation of the Furler meadows, 
typhoid fever had broken out, suddenly and violently, in 
Lausen. 

In order to make matters, if possible, more certain, the 
following experiments were made, but unfortunately not 
until the end of August when the water of the Lausen 
supply had again become clear. The hole which had 
appeared ten years earlier, and had afterward been filled 
up, was reopened, and the little brook was once more led 
into it; three hours later the Lausen fountains were 
yielding double their usual volume. A quantity of brine 
containing about eighteen hundred pounds of common 
salt was now poured into the brook as it entered the hole, 
whereupon there appeared very soon in the Lausen water, 
first a small, later a considerable and finally a very strong, 
reaction for chlorine, while the total solids increased to 
an amount three times as great as before the brine was 
added. In another experiment, five thousand pounds of 
flour (Mehl), finely ground, were likewise added to the 
brook as it disappeared in the hole ; but this time there was 
no increase of the total solids, nor were any starch grains 
detected in the Lausen water. 

It was naturally concluded from these experiments that 
while the water of the brook undoubtedly passed through 
to Lausen and carried with it salts in solution, it neverthe- 
less underwent a filtration which forbade the passage of 
suspended matters as large as starch grains. Dr. Hagler, 
from whose report the foregoing facts are taken, was careful, 
however, to state that " it is not denied that small organized 



TYPHOID FEVER IN LAUSEN, SWITZERLAND 191 

particles, such as typhoid fever germs, may nevertheless 
have been able to find a passage." As a matter of fact Dr. 
Hagler's minute account does to-day give us some indication 
that such germs might easily have passed from the brook to 
Lausen, for the turbidity of which he repeatedly speaks is 
evidence of the passage of particles probably as small as, 
and possibly smaller than, the germs of typhoid fever. 
( Typhus und Trinkwasser, Vierteljahrschrift filr bjfentliehe 
Gesundheitspflege, VI, 154; also Sixth Report, Rivers Pol- 
lution Commission of 1868. London, 1874.) 

Unfortunately, this was before pure cultures of bacteria 
were known, and no experiments were made with suspended 
matters as small as bacteria. The conclusion was inevi- 
table that although filtration had in this case sufficed to 
remove starch grains, it had been powerless to remove the 
germs of typhoid fever; and, accordingly, filtration as a 
safeguard against disease in drinking water fell for a time 
into disrepute. 1 

§ 7. — An Epidemic of Typhoid Fever in Caterham and 
Red Hill {England ) traced to a Polluted and Infected 
Ground Water Supply 

A number of epidemics of typhoid fever had been already 
traced with more or less certainty to polluted water supplies 
when, in 1879, there appeared a serious outbreak of this 
disease in the towns of Caterham and Red Hill in England. 
The duty of investigation of this case was fortunately as- 
signed to Dr. Thorne-Thorne, and his report which appears 
in the Report of the Medical Officer of the Local Govern- 
ment Board for 1879, pp. 78-92, is a model of careful 
investigation and sound reasoning. Briefly summarized, 
it was as follows : The total number of cases affected 

1 See a paper by the author on The Rise and Progress of Water-Supply 
Sanitation in the Nineteenth Century. Journal New England Water Works 
Association, XV (1901), p. 330, No. 4. 






192 WATER AS A VEHICLE OF INFECTIOUS DISEASE 



during the epidemic proper was 352. The total number 
of deaths, 21. The disease was typical typhoid fever, the 
patients exhibiting the characteristic rose-spots and diar- 
rhoea and some of them suffering from severe pulmonary 
and intestinal complications, the latter including perfora- 
tion of the bowels which, in four cases, was the immediate 
cause of death. The first person attacked sickened on 
January 19, 1879; a second, on the 20th; two more on 
the 23d ; three on the 24th, and thenceforward up to Feb- 
ruary 2, to which date information was at first limited, 
fresh attacks in fresh houses occurred day by day. 

Caterham lies in the rural sanitary district of Godstone, 
and had a population of about 5800. It included at this 
time a portion called Lower Caterham, near the head of the 
Caterham valley, a valley bounded by chalk hills. The 
houses in this part consisted mainly of superior villa resi- 
dences. The other or upper part lies at a higher altitude. 
Here, also, are a number of villas, one of the asylums be- 
longing to the Metropolitan District Asylums Board, and 
certain barracks. 

The cases of typhoid fever referred to, and which had 
occurred in the fortnight ending February 2, were 
spread over a very wide area, some in Upper and some in 
Lower Caterham, extending to the extreme outskirts of 
both places. The families attacked belonged to no special 
class, both rich and poor having suffered. It was appar- 
ent that the disease could not have been conveyed by 
means of any general system of sewers for the majority of 
the houses drained into separate cesspools. There was 
also no possibility that there had been any common cause 
of infection in connection with the prevailing means of 
excrement disposal, because there was nothing in common 
with regard to such disposal. The possibility of infection 
by means of milk supply was next inquired into, but dis- 
proved. It was also evident that personal infection could 
not in any way have led to the outbreak. Finally, it was 



TYPHOID FEVER IN CATERHAM, ENGLAND 193 

stated that for some years past the locality had been 
remarkably free from the disease, and only one isolated 
case could be heard of as having occurred during the 
twelve months preceding the outbreak, and this case was 
believed to have been imported. 

Caterham was supplied with water by the Caterham 
Waterworks Company, and of the forty-seven persons 
attacked during the fortnight in question, forty-five re- 
sided in houses supplied with this water. Suspicion 
was thus directed to the water supply, and was confirmed 
when it was ascertained that the two remaining patients, 
though living on premises having private wells, had been 
in the habit of spending the day at houses supplied 
with the company's water, and had admittedly used this 
water. 

It further appeared that in the Caterham Asylum, having 
nearly two thousand patients, no typhoid fever had ap- 
peared, and that there had been a similar absence of the 
disease among the five hundred men in the barracks. 
Both these establishments derived their entire water from 
a well sunk 462 feet into the chalk. 

In the meantime, information arrived that typhoid fever 
was also epidemic in Red Hill, a neighboring community. 
Red Hill had an estimated population of 9500, and included 
two or more villages, besides an asylum for idiots. It was 
about eight miles distant from Caterham, lay on a different 
geological formation, and was well sewered. Nevertheless, 
in regard to typhoid fever, the two places were remarkably 
similar. In both, the epidemic began at about the same time. 
The first two cases in Red Hill occurred on January 20; 
three more on the 21st; five more on the 2 2d; twelve on 
the 23d, and at the end of the first fortnight, namely, by 
February 2, the total number of houses affected was 
96, and the number of patients had reached 132. 
There was nothing which threw suspicion upon the 
sewers. The community had been totally free from 



194 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

the disease for at least eighteen months, and there 
was no reason to suspect the milk supply. The water 
supply, on the other hand, was derived for the most 
part from the waterworks of the Caterham Waterworks 
Company, and a sanitary official, Mr. Jacob, independently 
of Dr. Thorne and the local officer in Caterham, had 
arrived at the conclusion that the Caterham water was in all 
probability the vehicle of the disease. Of the ninety-six 
houses affected during the first fortnight of the epidemic at 
Red Hill, ninety-one actually drew their water from the 
Caterham Company's mains, and the histories obtained with 
reference to the attacks in the remaining five cases were such 
as to confirm the impression that the Caterham Company's 
water had been the immediate cause of the epidemic. 
For example, at one of these houses where ultimately three 
persons were attacked, the supply, as was hitherto believed, 
had been exclusively derived from a rain water tank, but 
it was now ascertained that the Caterham Company's water 
was in addition procured surreptitiously; that at another 
house, for which there was apparently no water supply, the 
company's water was procured from a neighbor's ; and with 
regard to the remainder, the patients infected were not 
only persons who were employed where the company's 
water was in use, but several of them had partaken of the 
water at their meals. 

Certain localities in Red Hill, namely, Mead vale, having 
about 1 60 houses, and in Red Hill itself a group 
of 30 houses supplied with wells, were practically 
exempt from typhoid fever. Still more striking was the 
case in Reigate, a town which forms the western ward of 
the burough of which Red Hill is the eastern ward. Rei- 
gate had a population of about 8500, provided, however, 
with a different water supply; and this region escaped 
entirely, only two cases, undoubtedly imported from Red 
Hill, having occurred there. 

All the facts ascertained in connection with the course 



TYPHOID FEVER IN RED HILL, ENGLAND 195 

of the epidemic up to February 2 afforded very strong 
presumption that it had been caused by the use of the 
Caterham Company's water. Further developments made 
this view almost certain. 

The Waterworks Company derived its supply from 
two deep wells, situated about 30 feet apart, and about 
490 feet deep. Both were several feet in diameter. 
Moreover, they were connected, by three adits in the 
chalk. From the wells the water was pumped to reser- 
voirs, in which it was submitted to Clark's softening 
process. The reservoirs freely communicated, and from 
them the supply was delivered by gravitation. During 
the preceding twelve months a third well had been made, 
90 feet away from the others and of similar depth. 
From 1 86 1, and until the construction of the third boring, 
the water supplied by the company was held in high 
repute ; but since that time, and prior to the epidemic, 
complaints had been made with regard to the water. 
These were due to an unavoidable turbidity and to inter- 
ruptions in the process of softening. Apart from this 
turbidity and temporary hardness, there was no reason 
to believe that the water was objectionable; and consider- 
ing the deep sources of the supply, it was by no means 
apparent how the water could have been the means of pro- 
ducing an extensive epidemic of typhoid fever. Dr. Thorne 
inquired carefully into the possibility of contamination of 
the supply en route, but with negative results. He next 
sought to discover whether any contamination had taken 
place in the reservoirs or in the mains. But these sources 
also were satisfactorily excluded. Many other points re- 
lating to the method of distribution of the water were 
inquired into, but none led to any explanation of the cir- 
cumstances of the epidemic. 

It was next suggested that cesspool drainage or soakage 
of surface filth might have existed around the com- 
pany's wells. Certain cesspools were found in the vicinity, 



196 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

but after careful examination were excluded as probable 
sources of contamination. 

In the meantime facts were brought to light which led to 
an extension of the inquiry in another direction. It ap- 
peared that during the latter part of 1878 and the begin- 
ning of 1879, the company had constructed an adit from 
one of their old wells up to the new boring, which was then 
being sunk. This adit was in the chalk at a depth of 
445 feet. It was 6 feet by 4 feet in section and 90 feet 
long. A number of men were employed in the work, some 
of them being in the wells below, others on the surface. 
It was ascertained that one of the men who left work some 
time in January was reputed to have been ill, though no 
inquiries had been made concerning him since he quitted 
the works. This man was sought out, and eventually the 
following facts were obtained: — 

"J. K., aged thirty-two years, resided in Caterham, and was employed 
by the company as a laborer from October 25, 1878. The work assigned 
to him was that of ' loading-man,' he being employed in the adit below 
in attaching to a rope let down from above the buckets by which the 
excavated chalk was raised to the surface, and in again receiving those 
buckets when lowered full of bricks and cement required for the work 
in progress. From December 14 to December 29, J. K. was absent. 
When he returned he was in perfect health, but in about a week, that is r 
about January 5, 1879, he felt himself ailing. His symptoms, which, 
according to his statement, steadily increased, were at first loss of appe- 
tite, recurring attacks of shivering alternating with a feeling of heat,, 
great pains in the limbs which he attributed to rheumatism, but which, 
instead of being confined to any of the joints, were described both by 
himself and by his wife as an ' aching all over,' and diarrhoea. As the 
symptoms became aggravated, he was so exhausted during his work and 
became so 'giddified' that he was more than once drawn to the sur- 
face, and immediately on his return home he was compelled to go to 
bed. More than once his wife noticed that he was ' light-headed ' in 
his sleep. All this while the diarrhoea continued, the man making a 
great effort to remain at his work, because, as explained, he had had no 
employment between the 14th and the 29th of the previous month. 

" With reference to this man's diarrhoea, it is necessary to make the 
following explanation : Both from his own statement, and from that of 






TYPHOID FEVER IN CATERHAM AND RED HILL 197 

others, it appears that all the men who worked in the adit were ex- 
pected to make such preparation before descending the well that no 
occasion should exist for relieving themselves below ; but should such 
necessity ever arise, and should there be at such a time any difficulty or 
delay in their being drawn to the surface, the buckets which were regu- 
larly being raised to the surface were to be used for that purpose. J. 
K. states that he strictly complied with these regulations before de- 
scending, but that, notwithstanding all his efforts, the purging under 
which he was laboring was such that he was compelled to evacuate 
whilst in the adit * at least two or three times ' during each shift, the 
shifts lasting apparently from eight to twelve hours each, according to 
circumstances. Indeed, as time went on, the man's diarrhoea must 
have been considerable, for besides the attacks which came on whilst 
in the adit, he almost invariably suffered from it before descending, im- 
mediately after ascending, and also at his own house. So matters con- 
tinued until January 20, when work was again suspended for two days 
on account of a rise in the water level. But during the night of the 
2 1st he was so much worse that he was unable to rise next morning. 
According to his wife's statement, he found he could not stand when he 
got up, and returning to his bed, suffered from < shivering down the 
back, aching, and exhaustion'; and later on severe abdominal pain 
came on which compelled him to lie with his knees drawn up ; he was 
also i burning hot.' This pain was looked upon as 'cramp,' and was 
alleviated by linseed-meal poultices, which were applied by his wife. 
The more severe symptoms, including the diarrhoea, having subsided, 
he was two days afterward able to get up for a while, and from this 
time convalescence appears to have set in. No medical advice was 
sought, mainly, as he explained to me, owing to his straitened circum- 
stances. When I saw him, on February the 8th, he had the aspect of a 
man who had recently suffered from some acute disease ; he was still 
very weak, and it was obvious that he had greatly lost flesh." 

Dr. Thorne and Dr. Jacob with extreme care searched 
further into the history of this case, with the following 
result, in Dr. Thome's words : — 

" I have now no hesitation in taking it as a fact, that a man ill of 
enteric [typhoid] fever from January 5 to the end of the month was 
occupied during the first fortnight of that period at work in the well of 
the Caterham Waterworks Company. The fact, it will be observed, is 
not inferred from any consequences of it, but simply from what was 
seen and heard of the particular individual. 

" But now let us see what those consequences would have been. If 



198 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

this man's stools could by any means have found their way into the 
water of the well in which he had been working, and being enteric 
fever stools could thus have led to the development of the poison of 
that disease in the well, the effect on the water consumers ought to 
have been noticed within from about ten to fifteen days after the date 
when the diarrhoea first came on. And this, in effect, is precisely what 
did take place, the epidemic having commenced on January 19 and 20 
in Caterham and Red Hill, respectively. This remarkable concurrence 
of dates led to a more detailed inquiry as to the course of the man's 
diarrhoea whilst working in the adit. He admitted that the purging 
was very copious, in short, that it ' ran from ' him ; indeed, when at 
home, he was, because of the suddenness of its onset, unable to resort 
to the closet. He further admitted that, owing to his frequent use of 
the bucket whilst at work, complaints were made by his fellow-workmen 
on the surface ; but he stoutly denied that he had ever been so pressed 
by necessity, or so influenced by those complaints, as to relieve himself 
in the adit without waiting for a bucket. But even accepting his de- 
nial, there were undoubted means by which his evacuations could have 
found their way into the water. According to his statement, the bucket 
was used as a closet when it was empty, when half full, and when full ; 
he added, however, that when it was full he first took some of the chalk 
out and subsequently replaced it. During an earlier stage of my in- 
quiry I had occasion to descend one of these wells, and I noticed that 
any article let down by a rope, by its oscillations to and fro, came into 
constant and somewhat violent contact with the walls of the wells, and 
on inquiry of J. K. whether the same did not take place with the bucket, 
he admitted not only that this was so, but that some of its contents fre- 
quently fell over a stage into the water below. On further inquiry, he 
added that some portions of his evacuations probably did so also. And 
he further stated that the looseness of his bowels was such that the 
bucket itself must almost of necessity have been stained with them. 
This bucket, which was merely emptied out above, then received, as 
already explained, materials which were used in the construction of the 
works below. Here, then, were the stools of an enteric fever patient, 
from about January 5 onwards, getting into the Caterham Company's 
water and distributed with that water to the district served by the 
company. 

" Now we know from ample experience that enteric fever is produced, 
and produced with the maximum of certainty, when the specific evacua- 
tions of that disease are consumed by a population. Again, it is a mat- 
ter of experience that where enteric fever has been conveyed through 
water, some fortnight has to elapse between the distribution of the 
water and the occurrence of the disease among the community served 



TYPHOID FEVER IN CATERHAM AND RED HILL 199 

by it. But a fortnight after January 5 to 19, i.e. from January 19 to 
February 2, the disease became widely spread throughout Caterham 
and Red Hill ; the distribution of the fever being limited, as we have 
already seen, to houses supplied with the water of the Caterham Com- 
pany. There can, I think, be no doubt that we have in the man J. K. 
the cause of the disease which followed. 1 ' 

A further study by Dr. Thorne made with similar care 
showed that wherever the Caterham water indubitably went, 
typhoid fever was also distributed. A part of this latter 
investigation was particularly interesting. The village of 
Warlingham, lying about three miles from the Caterham 
Company's Works, was supplied by that company with 
water, and yet had no typhoid fever. It appeared in the 
sequel, however, that in order to add to the Caterham 
Company's supply during certain portions of the time 
when the Caterham wells were undergoing alterations and 
furnishing a diminished supply, water had been pumped 
into the Caterham Company's mains by the Kenley Water- 
works Company; namely, continuously every night after 
November 26, 1878, to January 3, 1879; resumed again 
from January 5 to 10, then discontinued until the nights of 
the 14th and 15th, finally ceasing on the morning of the 
1 6th. This water was therefore pumped into the Caterham 
Company's mains for the period January 5 to 9, during 
which the distribution of infection must have commenced. 
The Kenley water was not, however, mixed directly with 
the Caterham water. It was pumped in at one particular 
point, and that point was the extreme farther end of the 
Warlingham branch of the system. Furthermore, the ca- 
pacity of the main between Caterham and Warlingham, and 
of the branches of this main in Warlingham, was somewhat 
over 1 2,000 gallons. Accordingly, before the Kenley water 
could get to the Caterham Company's reservoirs, it had to 
fill the whole of the three-inch Warlingham main and its 
system of branches, besides one other larger main nearer to 
Caterham. It is therefore fair to suppose that the inhab- 






200 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

itants of Warlingham rarely, if at all, and probably never, 
during this time, received any of the Caterham water. In 
the end Dr. Thorne was led to believe that the almost com- 
plete exemption of Warlingham — for only a single case 
appeared there during the epidemic period — was powerful 
support to his views in regard to the true source of this 
epidemic. 

The total number of cases was 352, and the total number 
of deaths, 21, to the end of February. After that time 
only a few scattered cases occurred. The disease, as has 
been stated, was typical typhoid fever, the patients exhibit- 
ing the characteristic rose-spots, diarrhoea, etc. Most of 
the cases were of an exceptionally mild character, and the 
majority attacked were children. Amongst adults, women 
were more frequently attacked than men. The low fatality 
is noteworthy, and agrees with the theory of great dilution 
of the infectious material. 

§ 8. — An Epidemic of Typhoid Fever in Plymouth {Penn- 
sylvania) traced to a Polluted Surface Water Supply 

One of the most instructive epidemics in the annals of 
sanitary science is the epidemic of typhoid fever which 
sprang from a polluted water supply in Plymouth, Penn., 
in the spring of 1885. Plymouth at that time was a mining 
town of about eight thousand inhabitants. It had grown up 
rapidly, and was not in good sanitary condition ; but it was 
provided with an apparently excellent, though limited, pub- 
lic water supply derived from a mountain stream, travers- 
ing an almost uninhabited watershed. There were, in fact, 
on the watershed only two houses so placed as to be able 
to contaminate the supply. It would appear from the ex- 
cellent report of Dr. L. H. Taylor, 1 of Wilkesbarre, from 
which the present account is drawn, that the inhabitants 

1 First Annual Report, State Board of Health and Vital Statistics of Penn- 
sylvania, pp. 176-195. Harrisburg, Penn., 1886. 



TYPHOID FEVER IN PLYMOUTH, PENN. 201 

of one or both of these had nevertheless for some time, 
perhaps for years, been polluting the public supply of 
Plymouth with ordinary faecal matters; but no harm was 
observed or even suspected until April, 1885, when, as was 
afterward discovered, the specific infection of typhoid fever 
was superadded to ordinary faecal pollution. Thereupon, 
out of a population of about 8000 persons, n 04 con- 
tracted typhoid fever, and 1 14 died. The story may be 
briefly told. 

" The first case belonging to this epidemic occurred on April 9, and 
from this time on the disease spread rapidly. During the week begin- 
ning April 12, from fifty to one hundred new cases appeared daily, 
and on one day it is said two hundred new cases were reported. . . . 
Various theories were put forth, some declaring it [the epidemic] to be 
due to the filth of the town ; some that it was due to drinking polluted 
well water ; others, polluted river water ; and still others that it was due 
to a peculiar condition of nature, by no means explainable. 

" Among the various theories advanced, one of the first was that it was 
due to the accumulated filth of the town, which, being acted upon by 
the warm rays of the April sun, had suddenly become noxious, and the 
emanations, therefore, had caused the disease. This especially suited 
the ' typho-malarial ' theorists. But although Plymouth was not an espe- 
cially clean town, it was not, on the other hand, more filthy than other 
neighboring towns where the disease did not prevail, nor was it at this 
particular time in worse condition than in preceding years. . . . 

" All classes of people were attacked, the clean as well as the filthy, 
and all parts of the town affected, the highlands as well as the valley 
. . . and thoughtful minds naturally turned to the water supply as fur- 
nishing the true cause of the invasion." 

In addition to certain wells and springs the inhabitants 
had access to one or both of two public water supplies. A 
small portion of the town received regularly water from the 
Susquehanna River, pumped by the Delaware and Hudson 
Coal Company, and those who used this water exclusively 
did not suffer from the disease. The greater portion, how- 
ever, was supplied by the Plymouth Water Company, 
which in 1876 began supplying the town "with water of 
remarkable purity, from a neighboring mountain stream 



202 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

which had its source in a beautiful sand spring some miles 
away." On the stream had been built, successively, four 
storage reservoirs: No. i, the first, the lowest, and that serv- 
ing as the distributing reservoir (see diagram), having a 
capacity of 300,000 gallons ; No. 2, next above, a capacity 
of 1,700,000 gallons; No. 3, still higher, of 3,000,000 gal- 
lons ; and finally, No. 4, highest of all, of 5,000,000 gallons. 
In spite of this storage capacity, however, the supply was 
at times insufficient, and was then supplemented by direct 
pumping from the Susquehanna River, a stream polluted, 
and at times infected, by the sewage of Wilkesbarre, a city 
of 30,000 inhabitants, lying on the same river only three 
miles above. "Water from the river was first pumped . . . 
in 1878, and occasionally in succeeding years, e.g. in 1881, 
91 days; in 1882-1883, ... 65 days; 1883-1884, 124 
days; 1884 [additional], 118 days. This water, though 
objectionable, . . . has never been followed by any [re- 
ported] epidemic of typhoid fever." 

In the spring of 1885 resort was again had to the river, 
which was used just before the epidemic appeared, viz. 
from March 20 to 26, 1885. Dr. Taylor was therefore 
obliged to consider very carefully the possibility that the 
source of the epidemic lay in the river water. He was able, 
nevertheless, by various independent lines of evidence, to 
show conclusively that the great epidemic, which began 
with a single case on April 9, and by the end of another 
week had risen to alarming proportions, could not possibly 
be attributed to the use of the sewage-polluted river water. 
It was easy to show that the milk supply and the well- 
water and spring-water supplies could not furnish adequate 
explanation of the epidemic, so that there remained only 
the mountain supply of water to be investigated. 



" There remains but one possible cause for this most serious and de- 
plorable outbreak, and that is contamination of the water supplying the 
company's reservoirs. A glance at the accompanying map will show 
the location of this stream and of the several reservoirs. Above the 



TYPHOID FEVER IN PLYMOUTH, PENN. 203 

starting point of the water pipes there is but one house situated upon 
the banks of this stream, and one upon the banks of the fourth 
reservoir. 

u In the house between the third and fourth reservoirs, situated 
almost immediately upon the stream, there lives a man who but recently 
has recovered from the effects of a severe attack of typhoid fever. This 
patient went to Philadelphia, December 24, 1884, and while there, he 
thinks, contracted the disease. Whether he did thus contract the dis- 
ease in Philadelphia may, we think, admit of question. But it is never- 
theless true that he returned to his home, January 2, 1885, and for many 
weeks was seriously ill with genuine typhoid fever. Early in March he 
was convalescent and was out of bed. A relapse occurred about the 
middle of March, and he was very sick on the 16th. On March 16 and 
17 he had hemorrhages of the bowels of so severe a type that, on March 
18, his life was despaired of, even by his physician. 

"He, however, rallied, was quite ill for some time, but was con- 
valescent in April, so that his physician discontinued his visits after 
April 12. 

" During the course of his illness, his dejecta passed at night, with- 
out any attempt at disinfection, were thrown out upon the snow and 
frozen ground, toward and within a few feet of the edge of the high 
bank, which slopes precipitously down to the stream supplying the town 
with water. 

" The nurse in charge states explicitly that in emptying the chambers 
at night she did not stand on the porch to throw out the contents, but 
stepped down some distance and threw them into the creek. If she 
stepped but a few feet away from the porch, she would empty the ex- 
creta within twenty-five or thirty feet of the edge of the stream. 

" The dejecta passed during the day were emptied into a privy a little 
farther back, the contents of which lie almost upon the surface of the 
ground, and at the first thaw or rain they too would pass down the slop- 
ing bank and into the stream. These dejecta were thrown out from 
time to time until the accumulation no doubt equalled the daily passages 
from many such patients. They remained innoxious upon the snow and 
frozen ground until some time between March 25 and April 1, when they 
were washed into the stream and thence into the third reservoir. 

"The house in question does not stand in a ravine nor in a pro- 
tected spot, but in an open clearing, with land sloping toward the south, 
which clearing would naturally feel the effects of the sun's rays and part 
with its snow and accumulated filth sooner than the more protected re- 
gions which also drain into the stream, so without cavil the first water 
from the effects of the thaw to enter the third reservoir would be from 
the melted snow in the immediate vicinity of this house. 



204 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

"The maximum temperature . . . was on March 26, 46. 5 F. ; March 
27, 56 ; March 28, 43 ; March 29, 37 , increasing rapidly until April 4, 
when a temperature of 70 F. was reached. 

"March 26, with a maximum temperature of 46.5 F., is the first day 
on which any considerable thaw could occur. Upon the evening of this 
day, the superintendent of the water company visited the reservoirs to 
ascertain whether it would be allowable to discontinue the pumping of 
river water. He found the first and second reservoirs almost entirely 
empty, while the third was filling rapidly, the short pipe which allows 
the water to discharge from the bottom of the third into the stream lead- 
ing to the second reservoir being tightly frozen. 

" He caused a fire to be built to melt the ice in this pipe, and then 
stopped the river pumps. The honest act of an honest man, and sim- 
ply in the discharge of his duty and with kindliest intent. But of what 
a catastrophe was he the unconscious usher and hastener ! The water, 
with its accumulated typhoid fever poison, was discharged from the bot- 
tom of the third reservoir, ran down to the second, on to the first, and 
was thence distributed to the town, in all probability between the 28th 
of March and the 4th or 5th of April. 

" In considering the possibility of one patient poisoning more than a 
thousand in Plymouth, we must bear in mind all the attending cir- 
cumstances : — 

" 1 . The accumulation of weeks — which equalled the dejecta from 
many ordinary patients, and which lay for a time dormant upon the 
snow and frozen ground. 

"2. The nearness to the stream. The house is so situated that all 
of the excreta were thrown within a few yards of its banks, and the con- 
formation of the ground is such that its surface water could not possibly 
drain in any other direction. 

" 3. The unusually warm weather — which caused a sudden thaw and 
poured the surface water into the empty reservoir. 

" 4. The concentration of the poison in a small amount of water. 

" 5. The short distance to the town ; and finally, the possible previous 
preparation of the soil for the reception of this seed, which sprang at 
once into vigorous growth and ripened for an abundant harvest of 
death. 

" It would seem that the mere statement of facts, as found in the few 
preceding pages, is amply sufficient to explain the cause of this remark- 
able epidemic, and we need have no hesitation in declaring the pollution 
of the mountain stream, which supplies the reservoirs of the water com- 
pany of Plymouth, to be the sole cause of the remarkable outbreak of 
typhoid fever in this borough. 



TYPHOID FEVER IN PLYMOUTH, PENN. 205 

" During the period of pumping from the Susquehanna, the water in 
that river was lower than it had been at any time for years, and the 
surface was frozen tight. The city of Wilkesbarre, containing thirty 
thousand inhabitants, delivers its sewage directly into the Susquehanna, 
the mouth of the lower sewer emptying only two miles above the Ply- 
mouth Pumping Station, while the current is very rapid between the 
two towns. The water is further contaminated by refuse water from 
five or six lines as well as by the garbage from the abattoirs at Wilkes- 
barre. Notwithstanding this unusually filthy condition of the Susque- 
hanna River, it is beyond question entirely innocent of causing the 
epidemic. . . ." 

Dr. Taylor's conclusions were confirmed in all essential 
particulars by other students of the epidemic, among whom 
may be mentioned Drs. Shakespeare and French of Phila- 
delphia ; Briggs of Buffalo ; and Biggs, Taylor, Edson and 
others, of New York. The first to suggest publicly the 
pollution of the mountain supply as the probable cause of 
the epidemic was Dr. R. Davis (in a Wilkesbarre newspaper 
published on April 29). 

We may readily agree with Dr. Taylor in his conclu- 
sions : — 

" It is safe to say that this was one of the most remarkable epidemics 
in the history of typhoid fever, and it teaches us some important lessons, 
at fearful cost. One is, that in any case of typhoid fever, no matter how 
mild, nor how far removed from the haunts of men, the greatest possible 
care should be exercised in thoroughly disinfecting the poisonous stools. 
The origin of all this sorrow and desolation occurred miles away, on 
the mountain side, far removed from the populous town, and in a soli- 
tary house situated upon the bank of a swift-running stream. The at- 
tending physician did not know that this stream supplied the reservoirs 
with drinking water. Here, if any place, it might seem excusable to 
take less than ordinary precautions ; but the sequel shows that in every 
case the most rigid attention to detail in destroying these poisonous 
germs should be enjoined upon nurses and others in charge of typhoid 
fever patients, while the history of this epidemic will but add another to 
the list of such histories which should serve to impress medical men, 
at least, with the great necessity for perfect cleanliness — a lesson which 
mankind at large is slow to learn. 

" Another lesson taught by this history comes more nearly home to 
us all. The water-companies throughout our land should be taught 



206 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

that they must furnish us the water for which we pay, from the very 
best source which the country affords. Not only should they avoid the 
use of river water contaminated by sewage, but they should be com- 
pelled to remove from the banks of their streams and reservoirs not 
only all probable, but all possible sources of pollution." 

Dr. M. S. French made an interesting estimate of the 
financial waste or loss involved in the Plymouth epidemic, 
and his paper, which follows that of Dr. Taylor (pp. 196- 
217, /. c), contains also a complete and impressive list by 
name of those attacked with typhoid fever. Dr. French 
estimates the cost of the sickness — " expenses incurred by 
the epidemic " — at $67,100.17, of which $8,000 were spent 
in maintaining a temporary hospital. 

" Of those who were ill with the disease and recovered, 
the loss of earnings during their illness was found to be 
$30,020.08. Thus the total cost of the epidemic is reckoned 
at $97,120.25. By the 114 deaths, a monthly earning of 
$1,534.96 ceased, showing a loss of $18,419.52 per year in 
incomes." 

Dr. French does not, as he might have done, capitalize 
this latter sum, and add the result to the gross loss ; if he 
had done so, he might have concluded that the total cost of 
this disastrous epidemic was more than half a million of 
dollars. It will be observed that the fatality (1 14 deaths in 
1 104 cases) was much higher than in the Caterham epi- 
demic (21 deaths in 352 cases), or 10.3 per cent against 5.9 
per cent, and that this corresponds well with the probable 
relative concentration of the infectious material in the two 
epidemics. 



THE COST OF AN EPIDEMIC 207 

§ 9. — Typhoid Fever in Loivell, Lawrence and Other 
Cities on the Merrimac River 

In the valley of the Merrimac River, which is a large, 
swift stream draining a considerable portion of southern 
New Hampshire and northern Massachusetts, are situated 
a number of cities and towns of which the history in re- 
spect to typhoid fever is interesting and instructive. Situ- 
ated in the same valley, under closely similar climatic 
conditions, they are also, for the most part, manufacturing 
towns or cities, and have populations especially favorable 
for purposes of sanitary comparison. Lowell, Lawrence 
and Manchester are devoted chiefly to textile industries, 
and nearly the same might be said of Nashua and Con- 
cord, while Haverhill is what is called a "shoe " town, and 
Newburyport, while possessing some textile industries, is 
more diversified in this respect. 

In connection with his duties as biologist to the State 
Board of Health in Massachusetts, and especially with his 
work at the Lawrence Experiment Station of that Board, 
the author was already somewhat familiar with the sanitary 
history of the cities and towns situated in the Merrimac 
Valley, when, in December, 1890, a serious epidemic of 
typhoid fever having appeared in the city of Lowell, 
lying only nine miles above Lawrence, he was instructed 
by the Board to make a thorough investigation. At 
almost the same time he was also invited by the Water 
Commissioners of Lowell to conduct a similar inquiry on 
their behalf. Accordingly, clothed with ample authority 
and provided with every opportunity, he set to work. 

The population and death-rates from typhoid fever in 
the principal cities of the Merrimac for the two years 
preceding the outbreak of the great epidemic of 1 890-1 891 
are shown in the following tables : — 



208 WATER AS A VEHICLE OF INFECTIOUS DISEASE 



TYPHOID FEVER IN THE PRINCIPAL CITIES ON THE 
MERRIMAC RIVER 

Deaths per ioo,ooo Inhabitants (Population from United States 
Census of 1890) 

1888-1889 





=3 

0. 
< 


£ 

s 


O 

S3 

3 


"3 


3 
M 
3 
< 


u 

1 

V 

a. 
u 

CO 


M 
V 

| 
O 

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> 



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.n 
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f5 4) 


Concord, N. H 


.0 


.0 


.O 


.0 


5-9 


17.6 


17.6 


17.6 


11.8 


.O 


.0 


.0 


70-S 


Manchester, N. H. . . . 


.0 


2-3 


4.6 


.0 


.0 


4.6 


• O 


6.9 


6.9 


2-3 


.0 


2-3 


29.9 


Nashua, N. H 


5-3 


.0 


.O 


.0 


.0 


15-9 


31.8 


5-3 


10.6 


.0 


.0 


.0 


68.9 


Lowell, Mass 


10.4 


7.8 


3-9 


3-9 


3-9 


10.4 


6.5 


9.2 


9.2 


5-3 


6.6 


9.2 


86.3 


Lawrence, Mass. . . . 


11. 2 


9.0 


11. 2 


2.2 


9.0 


.0 


17.9 


13-4 


13-4 


4-4 


15.6 


17.9 


125.2 


Haverhill, Mass. . . . 


.0 


.0 


3-8 


.0 


3-8 


3-8 


3-8 


.0 


.0 


3-8 


3-8 


•O 


22.8 


Newburyport, Mass. . . 


.0 


.0 


.0 


.0 


.0 


.0 


.O 


.0 


7.2 


.0 


7.2 


.O 


14-4 



1889-1890 





9 


£ 

§ 


a 
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>> 

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3 
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3 


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3 

u 

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fa 


.3 
u 


3 4> O 


Concord, N. H 


5-9 


5-9 


.0 


S-9 


.O 


.0 


11.8 


.0 


.0 


.0 


.0 


.0 


29. 5 


Manchester, N. H. 




2.3 


.0 


2.3 


2.3 


7-0 


4-7 


47 


9-3 


4-7 


45 


.0 


.0 


41.8 


Nashua, N. H. . . 




.0 


.0 


.0 


.0 


•O 


.0 


5-3 


10.7 


5-3 


5-3 


10.6 


5-3 


42-5 


Lowell, Mass. . . 




9.2 


6.6 


4.0 


i-3 


6.6 


9.2 


4.0 


11.9 


11.9 


6.4 


77 


5-i 


83.9 


Lawrence, Mass. . 




8.9 


8.9 


11. 2 


4.4 


6.7 


i 5 .6 


8.9 


6.7 


i3-4 


iS-6 


13-4 


4.4 


118.1 


Haverhill, Mass. . 




3-8 


.0 


.0 


3-8 


3-8 


.0 


7-5 


.0 


3-8 


3-8 


3.8 


.0 


30-3 


Newburyport, Mass. 




.0 


7.2 


.0 


14.4 





.0 


.0 


.0 


.0 


7.2 


.0 


.0 


28.8 



TYPHOID FEVER IN THE MERRIMAC VALLEY 209 

The death-rates for the epidemic years 1 890-1 891 are 
shown in the following table : — 

TYPHOID FEVER IN THE PRINCIPAL CITIES ON THE 
MERRIMAC RIVER 

Deaths per 100,000 Inhabitants (Population from United States 
Census of 1890) 

1890-1891 





"3 

ft 

< 




a 

3 
>-> 


"3 


3 
to 

3 


x> 
S 
<u 

a. 





| 

O 


& 

V 

> 


to 


6 

V 

V 

Q 


b 

9 

3 
a 

a! 


3 




OJ=5 


Concord, N. H 


5-9 


11.8 


.0 


.0 


11.8 


17.6 


.0 


.0 


.0 


.O 


.O 


5-9 


53-o 


Manchester, N. H. 




.0 


2.3 


.0 


2-3 


4.6 


6. 9 


.0 


6.9 


11.4 


4.6 


4.6 


.0 


43-6 


Nashua, N. H. . . 




.0 


.0 


.0 


.0 


.0 


.0 


.0 


.0 


.0 


• O 


5-3 


.0 


5-3 


Lowell, Mass. . . 




7.8 


10.4 


11.6 


7.8 


7.8 


12.9 


12.9 


36.3 


32.3 


24.6 


18.1 


12.9 


195-4 


Lawrence, Mass. . 




11. 2 


.0 


11. 2 


2.2 


2.2 


4-5 


11. 2 


15.6 


42.6 


47.O 


26.9 


13-4 


187.0 


Haverhill, Mass. . 




7-5 


3-8 


.0 


7-5 


.0 


"•3 


.0 


3.8 


.0 


.O 


.0 


.0 


33-9 


Newburyport, Mass. 




.0 


.0 


7.2 


.0 


.0 


14.4 


21.6 


.0 


7.2 


7.2 


.0 


.0 


57-6 



The death-rates for the same cities for the two years 
next after the great epidemic of 1 890-1 891 are shown in 
the following tables : — 

TYPHOID FEVER IN THE PRINCIPAL CITIES ON THE 
MERRIMAC RIVER 

Deaths per 100,000 Inhabitants (Population from United States 
Census of 1890) 

1891-1893 





ft 

< 


2 


c 

3 


"3 


3 
to 

3 
< 


u 

in 


u 

4) 


O 


6 


to 


u 

,0 

e 

4) 


£ 

3 
3 
rt 

•— 1 


3 
En 







,0 « « 
™ *■£ 
a a 


Concord, N. H 


5-9 


.0 


.O 


.0 


I7.6 


.0 


5-9 


.0 


.O 


.O 


.0 


.0 


29.4 


Manchester, N. H. . . 


23 


.0 


2-3 


.0 


.O 


.0 


.0 


.0 


.O 


4.6 


.0 


2-3 


«S 


Nashua, N. H 


.0 


.0 


.0 


.0 


15.8 


15.8 


10.6 


31-7 


5-3 


5-3 


5-3 


.0 


89.8 


Lowell, Mass 


7.8 


5-2 


i-3 


5-2 


3-9 


3-9 


9.1 


3-9 


2.6 


16.8 


10.4 


11.6 


81.7 


Lawrence, Mass. . . . 


6.7 


4-5 


2.2 


2.2 


2.2 


11. 2 


6.7 


9.0 


2.2 


11. 2 


lS-6 


17.9 


91.6 


Haverhill, Mass. . . . 


7-5 


.0 


.0 


.0 


3-8 


.0 


.0 


3-8 


3-8 


7-5 


3-8 


.0 


30.2 


Newburyport, Mass. . . 


.0 


7.2 


7.2 


° 


•° 


.0 


7.2 


.0 


7.2 


.0 


.0 


.0 


28.8 



210 WATER AS A VEHICLE OF INFECTIOUS DISEASE 



1893-1893 





< 




3 




1 
3 
<5 


1 
S 
« 
a. 
u 
C/3 


u 
1) 




U 

> 



u 

1 

Q 


3 
C 
CO 


>> 

2 

fa 


•3 

u 


5 4) O 
r 0, S§ 


Concord, N. H 


.0 


5-9 


.O 


.0 


.0 


.O 


.0 


.0 


5-9 


.0 


.O 


.0 


11.8 


Manchester, N. H. 




2-3 


.0 


4.6 


6.9 


.0 


2-3 


.0 


.0 


2.3 


2-3 


.O 


.0 


20.7 


Nashua, N. H. . . 




.0 


.0 


.O 


.0 


.0 


5-3 


.0 


15-9 


5-3 


.0 


5-3 


.0 


31-8 


Lowell, Mass. . . 




5-2 


9.1 


2.6 


5-2 


5-2 


9.1 


5-2 


3-9 


12.9 


12.9 


9.1 


5-2 


83.6 


Lawrence, Mass. . 




6.7 


2.2 


4-5 


9.0 


4-S 


.0 


6. 7 


9.0 


20.1 


6.7 


26.8 


17.9 


114.1 


Haverhill, Mass. . 




3-8 


.0 


3-8 


3-8 


.0 


7-5 


.0 


3-8 


22.5 


.0 


150 


3-8 


64.0 


Newburyport, Mass. 




.0 


14.4 


.0 


.0 


.0 


.0 


.0 


.0 


7.2 


21.6 


.0 


7.2 


SO-4 



The death-rates from typhoid fever for twelve-month 
periods in the principal cities on the Merrimac River, 
for five years in succession, are shown on the following 
table: — 



DEATH-RATES FROM TYPHOID FEVER, BY PERIODS OF 
TWELVE MONTHS, IN THE PRINCIPAL CITIES ON THE 
MERRIMAC RIVER, FOR THE FIVE YEARS, APRIL 1, 1888, 
TO MARCH 31, 1893. 

Deaths per 100,000 Inhabitants (Population from United States 
Census of 1890) 





From 


From 


From 


From 


From 


Average 




Apr., 1888, 


Apr., 1889, 


Apr., 1890, 


Apr., 1891, 


Apr., 1892, 


Apr., 1888, 




to 


to 


to 


to 


to 


to 




Mar., 1889 


Mar., 1890 


Mar., 1891 


Mar., 1892 


Mar., 1893 


Mar., 1893 


Concord, N. H. . . . 


7°-5 


29-5 


53-o 


29.4 


11.8 


38.8 


Manchester, N. H. . . 


29.9 


41.8 


43-6 


"•5 


20.7 


29.5 


Nashua, N. H. . . . 


68.9 


42.5 


5-3 


89.8 


31-8 


477 


Lowell, Mass. . . . 


86.3 


83-9 


195-4 


81.7 


85.6 


106.61 * 


Lawrence, Mass. . . 


125.2 


118.1 


187.0 


91.6 


114.1 


127. 2. * 


Haverhill, Mass. . . 


22.8 


303 


33-9 


30.2 


64.0 


463 


Newburyport, Mass. 


14.4 


28.8 


57-6 


28.8 


50.4 


36.0 



A very brief consideration of the facts laid down in this 
table reveals certain striking phenomena. In the first 
place, it is evident that none of these cities was free from 

1 Excluding 1890-1891 (the period of the great epidemic), the average for the other four 
years is 84.4 for Lowell, and for Lawrence, 112.25. 



TYPHOID FEVER IN LOWELL AND LAWRENCE 2 1 1. 

typhoid fever, at least for any considerable length of time. 
In the second place, on the whole (as seen from the last 
column of the last table), the average amount of typhoid 
fever in all the cities excepting Lowell and Lawrence was 
very much the same. All the tables, however, display a 
marked excess of typhoid fever in Lowell and Lawrence 
over that in the other cities, and in the year of the great 
epidemic (1 890-1 891) this excess is especially notable. 
Those who desire to follow the facts in detail are referred 
to the original reports of the author. 1 The main points, 
however, will be touched upon here. 

It has already been stated that these cities are closely 
similar in climate and pursuits, and the same thing may be 
said of them in every other important respect excepting 
one, namely, their water supply, which in the cases of 
Lowell and Lawrence only, during these years and for 
some years preceding, had been derived directly from the 
Merrimac River, a sewage-polluted stream, without any 
attempt whatever at purification. The water supplies of 
Concord, Nashua and Haverhill and, during most of the 
time, of Newburyport, on the other hand, were derived 
from other sources, as a rule entirely unobjectionable, 
and in some cases, as for example that of Nashua, re- 
markably pure. 

When in the autumn of 1890 the great epidemic of 
typhoid fever broke out in Lowell, one even more severe 
soon after appeared in Lawrence. The former was traced 
to an unusual infection of the Merrimac River by cases of 
typhoid fever in a suburb of Lowell, through a little feeder 
of the river known as Stony Brook, which entered it only 
three miles above the intake of the waterworks. That in 

1 On recent epidemics of typhoid fever in the cities of Lowell and Lawrence 
due to infected water supply, with observations on typhoid fever in other cities 
and towns of the Merrimac valley, especially Newburyport. Illustrated by 
maps, photographs, etc. Twenty-fourth Report (for 1892) State Board of 
Health of Massachusetts, pp. 667-704. Boston, 1893. 






212 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

the latter was plainly due to the same cause, to which was 
added the pollution and infection of the river by the sew- 
age of Lowell (at that time a city of eighty-five thousand 
inhabitants), the sewers of which emptied into the river 
only nine miles above the intake of the Lawrence water- 
works. There were all together probably upward of fifteen 
hundred cases of the disease in the two cities, as a result of 
this infection of the public water supplies. 

A number of interesting facts were developed as the 
result of careful studies made of this epidemic by Mr. 
Hiram F. Mills, 1 Mr. George V. McLauthlin, and the 
author. It was discovered, for example, by Mr. Mills, 
that Lowell and Lawrence had long suffered annually 
from two autumn increments of typhoid fever, instead of 
one as is customary in most places, and that the first was 
contemporaneous with that in other cities and towns of the 
state, while the second arrived considerably later. The 
latter was evidently due to the fact that the water supplies 
of the two cities had become infected as a result of the 
usual autumn increment of the disease in the cities and 
towns on the river above, so that the second increment 
was a crop of which the first was the seed. 

It was discovered by the author that the problem of 
typhoid fever in these cities was much complicated by the 
prevailing custom in both of distributing in the numer- 
ous mills and factories water so placed as to be acces- 
sible for drinking purposes (and in fact much used by 
the operatives of whom the population is largely com- 

1 To Mr. Mills, the distinguished hydraulic engineer, whose paper largely 
devoted to this epidemic (" Typhoid Fever in its Relation to Water Supplies," 
Twenty-second Annual Report State Board of Health of Massachusetts, for 
1890, pp. 525-543) is of great interest and value, sanitary science is under 
deep obligations for many years of able, disinterested, volunteer service. 
In Mr. McLauthlin, whose early death cut short a career of unusually brilliant 
promise, sanitary science lost an enthusiastic, devoted and tireless worker, 
whose labors in epidemiology for the State Board of Health of Massachusetts 
deserve remembrance. 



TYPHOID FEVER IN LOWELL AND LAWRENCE 213 

posed), which was derived directly and unpurified from 
little branches of the river (called canals) used for power, 
washing, etc., by the mills, which were in some cases pol- 
luted within the city itself by excreta from other mills, the 
public hospital, privies, etc. 

The Lowell and Lawrence epidemic of 1 890-1 891, on the 
Merrimac River, also threw great light on the interpreta- 
tions properly to be put upon chemical water analyses, and 
on the theory of the self -purification of streams ; for the 
chlorine present in the river at Lowell was no greater 
than that often observed in good drinking water (owing to 
the rising of the river far from the sea, the source of the 
chlorine in the natural waters of New England), although 
it was known to have received en route vast quantities of 
sewage from the towns and cities on its banks ; and while it 
had seemingly been purified by its long journey, it was plain 
from the vital statistics of the two cities — and especially 
those of Lawrence as compared with Lowell — that puri- 
fication had been only too incomplete. Thanks to the 
careful investigations of Professor (now President) Drown, 
chemist of the State Board of Health of Massachusetts, 
the former error was easily detected by a determination of 
the " normal chlorine " of the river at its source. The 
latter error (the seemingly trustworthy " self-purification ") 
was readily accounted for by a careful consideration of the 
natural and heavy contribution to the river of well-filtered 
ground water, which serves to dilute, and possibly to 
damage, but not necessarily to destroy, microbic life. 

§ 10. — Pollution versus Infection 

A study of the facts given in the preceding paragraph 
proves what is now well known, namely, that the use of 
water polluted with ordinary sewage free from specific 
infection is not necessarily followed by harmful conse- 
quences. The great sewers of the cities on the Merrimac 



214 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

River above Lowell poured their sewage into the river con- 
stantly, and yet at times there was little or no typhoid 
fever in Lowell After the usual autumn infection of the 
river, however, typhoid fever abounded in Lowell (and 
later in Lawrence); and when in 1890 an extensive and 
unusual infection occurred on a near feeder of the Merri- 
mac, which had for many years poured in its sewage with- 
out marked effect, a great epidemic quickly broke out in 
both cities. There is every reason to believe that in the 
case of wells, springs, and other sources of water supply, 
the same law holds. Mere pollution with uninfected sew- 
age, or with thoroughly purified sewage, may do little or 
no harm. Something more than ordinary pollution is re- 
quired; there must be infection in the sewage and the 
presence of active, virulent and specific germs of disease. 
The same thing is illustrated by the case next to be con- 
sidered. 

§11. — The Case of Newburyport, Mass. 

In January, 1893, an outbreak of typhoid fever in the 
city of Newburyport, at the mouth of the Merrimac, 
furnished a striking and instructive demonstration of that 
difference which exists, and is too often forgotten, between 
general " pollution" and specific "infection." 

The city of Newburyport had for many years derived 
its drinking water from large springs of an unobjectionable 
character, and typhoid fever had been of rare occurrence 
when suddenly, in January, 1893, an unusual number of 
cases of typhoid fever broke out almost simultaneously, and 
an investigation of them was made by the author. It soon 
appeared that there were in all about thirty cases, and on 
inquiry it proved that, as the springs had yielded an insuffi- 
cient supply of water, a connection had been made with 
an intake pipe leading directly from the Merrimac River, 
through which the crude river water had been pumped into 
the pipes. It was also naively stated, by way of defence, 



POLLUTION VS. INFECTION 215 

that this water could not have caused the typhoid fever 
u because the same thing had been going on since August." 
Assuming this to be true, as appeared to be the case, it was 
an extremely interesting fact, because the health records 
of the numerous cities and towns pouring sewage into the 
river above Newburyport showed very little typhoid fever 
in any of them in that year until the December just previ- 
ous, at which time Lowell once more suffered from a small 
epidemic of typhoid fever, which seems to have borne 
its natural fruit in both Lawrence and Newburyport. In 
other words, as long as the people of Newburyport drank 
the waters of the Merrimac merely polluted with ordinary 
sewage, no typhoid fever (or other infectious disease) ap- 
peared ; but when the specific bowel discharges of typhoid 
fever were added to the sewage, this disease speedily broke 
out. (See report by the author on the Newburyport out- 
break, Twenty-fourth Annual Report State Board of Health 
of Massachusetts (for 1892), pp. 701-704.) 

From this and many other similar cases we have reason 
to believe that sewage-polluted water is ordinarily only a 
vehicle, and not usually in itself a source, of infectious 
disease. 

§ 12. — An Epidemic of Asiatic Cholera i7i Hamburg, Ger- 
many, traced to an Infected Public Water Supply 

The great epidemic of Asiatic cholera which occurred in 
Hamburg in 1892 was traced to an infection of the public 
water supply, probably due to the excrements of certain 
emigrants detained on ships in the Elbe while en route to 
America, and suffering from the disease in question. The 
water supply of Hamburg was at that time derived directly 
from the Elbe, and pumped, without purification of any 
kind, for the immediate use of the citizens. A neighboring 
suburb (Wandsbeck) and the city of Altona which forms 
virtually a part of Hamburg, remained almost entirely free 
from the disease. The former had an excellent water sup- 






il 



216 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

ply not drawn from the river ; the latter drew its water 
supply from the river, and from a point where it contained 
more sewage than did the Hamburg water, but with this 
difference : — the Altona water supply was purified by 
filtration before it was delivered to the consumers. Since 
the epidemic, Hamburg has also introduced excellent 
filters, with most satisfactory results. 

§ 13. — An Epidemic of Typhoid Fever in New Haven, 
Conn., due to an Infected Surface Water Supply 

In the spring of 1901, typhoid fever appeared in excess 
in one portion of the city of New Haven, Conn., which 
was served by a water supply distinct from those supplies 
serving the remainder of the city. In all about 450 cases 
appeared within one month. Investigation showed that 
the outbreak was, in kind, not unlike that in Plymouth, 
Penn. (described above). The excrements of typhoid fever 
patients in a single house had found their way during 
heavy rains into a reservoir, which had previously been 
drawn low, so that the infection was carried quickly, and 
while comparatively fresh, to the consumers of the water, 
with disastrous results. 

§ 14. — Diseases Other than Typhoid Fever and Asiatic 
Cholera traced to Polluted Drinking Waters 

It is an interesting and very important question whether 
or not diseases, other than those already described, are 
capable of transmission by drinking water, and we are at 
present unable to answer the question satisfactorily. It 
is easy to see that much must depend on the conditions 
surrounding any particular case. For example, cholera in- 
fantum, diphtheria and measles are seldom, if ever, charged 
to polluted water supplies, and yet there is very little doubt 
that if the stay in the water of their germs should be short 
enough, the germs would survive and do their character- 



WATER-BORNE DISEASES 217 

istic damage. The truth appears to be that water is a 
much less favorable vehicle for some germs — such as 
those of diphtheria — than for others — such as those of 
typhoid fever ; but in the present state of our ignorance it 
would be very rash to conclude that any particular germs 
may not, under favorable circumstances, be conveyed by 
drinking water acting as a vehicle. 

§ 15. — Dysentery and Diarrhoea 

In the case of dysentery and diarrhoea, there is no doubt 
whatever that drinking water may be, and often is, their 
ready vehicle. In almost all cases in which a pure water 
supply has been substituted for one impure, a marked 
diminution can be shown in the deaths attributed to these 
disorders. 1 

Previous to the improvement of the water supply of 
Burlington, Vt, in 1894, dysentery, and especially diar- 
rhoea, were relatively prominent among the assigned causes 
of mortality ; but since that time they have been insig- 
nificant. The case of Burlington, 2 in respect to diarrhoea, 
is peculiarly instructive. References to the local sanitary 
conditions of that city will be found on pp. 132, 234. In 
this connection it will suffice to state that in the early 
sanitary history of that city, when the water supply was 
drawn without purification from a point on the shore of 
Lake Champlain, relatively near the place where the prin- 
cipal sewer emptied into the same lake, typhoid fever and 
diarrhoea both prevailed, after a time, to an alarming de- 
gree. When, later (in 1885), the main sewer outfall was 
removed to a greater distance, typhoid fever diminished, 

1 See, for example, Dr. Buchanan's classical report, Ninth Report Medical 
Officer of the Privy Council, p. 16. London, 1867. 

2 See, on this subject, the author's paper, " On the Sanitary Condition, 
Past and Present, of the Water Supply of Burlington, Vt." Journal, Nezu 
England Waterworks Association, Vol. X, No. 3, pp. 167-183. 



I 



218 WATER AS A VEHICLE OF INFECTIOUS DISEASE 

but diarrhoea remained very prevalent. When, still later, 
in 1894, the sewage outfall and the water intake were still 
further separated, — the water intake having been carried 
out some three miles into "the broad lake," — endemic 
diarrhoea also disappeared. 

§ 16. — Concluding Remarks on Drinking Water as a 
Vehicle of Disease 

Space forbids extended treatment in this connection of 
many minor principles which have been worked out along 
the line of the epidemiology of diseases conveyed by water. 
A few of these may, however, be set down. One is that 
the intensity of the epidemic appears to depend largely on the 
amount and the freshness of the infection. That it depends 
on the amount is clear from the fact that the size of the epi- 
demics in Lawrence followed obviously the size of the cor- 
responding serious outbreaks in Lowell. That it depends 
on the freshness of the infection is shown, for example, by 
the tremendous effect upon Lowell of a small but near 
infection, while the same city had annually been exposed, 
without much doubt, especially in the autumn, to more 
extensive, but at the same time more remote, infection. 
The same thing is shown by the experience of Chicago. 
So long as water was derived from the two-mile crib, com- 
paratively little typhoid fever developed; but when, in 
1 89 1, water was drawn so that more and fresher germs 
were received, an epidemic of the most serious and threat- 
ening character appeared. 1 

Another interesting series of facts appears when we con- 
sider the local conditions on the Merrimac above Lowell. 
Inasmuch as the river is very low in summer, so that for 
weeks at a time it is wholly diverted into the canals at 
Lowell and Lawrence to be used for power in the mills, 

1 Sedgwick and Hazen, " Typhoid Fever in Chicago." Engineering News, 
New York, April, 1892. 






TYPHOID FEVER IN CHICAGO 219 

and inasmuch, further, as the sewers of the cities above 
these are constantly pouring their sewage into the river, it 
follows as a matter of course that at such times the amount 
of sewage in the river is relatively greater than at other 
times. It might, therefore, reasonably be supposed that a 
sewage-borne disease, such as typhoid fever, ought to be 
more abundant among those using the water at such times. 
It would also be expected that the bacteria which swarm 
so abundantly in sewage must be abnormally numerous in 
the river water at a time when sewage forms so large an 
element in its composition. 

The facts, however, are precisely the reverse of what 
might at first sight have been reasonably expected. 
Typhoid fever was comparatively rare among users of the 
Merrimac when the river was " low " and concentrated, 
and frequent when the river was " high " and the sewage 
dilute. Bacteria were also few, comparatively. On looking 
for the explanation of these facts it was found in the local 
conditions. It appears that when the river is "low," 
although the sewage which it contains forms a larger pro- 
portion of its whole volume than at other times, yet the 
river then becomes a series of comparatively quiet mill- 
ponds, fed largely by the purest water which ever enters 
the river, namely, well-filtered ground water nearly free 
from bacteria. Purified partly by dilution with this purer 
ground-water, and partly by the intense and long light of 
summer days, by sedimentation in the relatively slow and 
quiet stream, and probably also by the action of larger 
micro-organisms such as algae and infusoria, and even by 
higher plants such as Anacharis or Vallisneria, it finally 
comes to pass that the summer flowage is actually safer to 
drink than the impetuous freshets of the spring or autumn, 
which, though largely composed of rain water, in their vio- 
lence corrode the surface of the earth, and bear swiftly to 
the consumer of the river water not only the foul washings of 
the surface soil, but also, with small opportunity for purifi- 



220 WATER AS A VEHICLE OF INFECTIOUS DISEASE 









cation, the fresh sewage of even remote cities and towns. 1 
Hence the paradox, that when river water is freshest, it 
may be least safe ; and when richest in sewage, it is not 
necessarily most dangerous. 

The student of sanitary science is strongly advised to 
study in the most minute detail and, if possible, under a 
master in epidemiology, at least one epidemic of typhoid 
fever. Such epidemiological work is to the sanitarian what 
careful laboratory work is to the chemist, the physicist or 
the biologist. 

1 For an interesting and instructive example of the efficiency of relatively 
small and remote pollutions, see a report by the author on " The Sources of 
Typhoid Fever in Pittsburgh." Report of the Filtration Commission of the 
City of Pittsburgh, Penn. Pittsburgh, 1899. 



CHAPTER IX 

ON THE ESTABLISHMENT AND CONSERVATION OF PURITY IN 
PUBLIC WATER SUPPLIES 1 

" There is no river in the United Kingdom long enough to secure 
the oxidation and destruction of any sewage which may be discharged 
into it, even at its source." Rivers Pollution Commission of i868 f 
Sixth Report, p. 427. London, 1874. 

"The public is hitherto very imperfectly protected against certain 
extreme dangers which the malfeasance of a water company, supplying 
perhaps half a million of customers, may suddenly bring upon great 
masses of population. Its colossal power of life and death is something 
for which till recently there has been no precedent in the history of the 
world ; and such a power, in whatever hands it is rested, ought most 
sedulously to be guarded against abuse." — Sir John Simon, Ni?ith 
Report of the Medical Officer to the Privy Council, p. 28. London, 
1867. 

§ 1. — Public Supplies as Public Dangers 

A public supply is a public danger, and for two reasons : 
first, because it affects large numbers of people; and, second, 
because it is beyond their direct supervision and control. 
Along with the substitution of the convenience of public, 
for the inconvenience of private, supplies of gas, water, milk 
and transportation, goes inevitably the surrender of the 
privilege of private supervision and superintendence. This 
is one of the obvious disadvantages of urban life every- 
where, and especially of life in great cities. The social unit 
— the family — can as a rule no longer use its own well, its 
own cow, its own carriage. It must depend as a rule upon 

1 Originally prepared by the author as the " Middleton Goldsmith " lecture 
of the New York Pathological Society, and read by him before the Society, 
March 15, 1898. 

221 



222 PURITY IN PUBLIC WATER SUPPLIES 

the public water supply, the public gas supply, the public 
milk supply, the public vehicle. These, of course, are often 
cheaper and more convenient, but, unhappily, often also 
more dangerous. 

On the other hand, it is easy to see that public sup- 
plies may easily be made public safeguards. All that is 
necessary is to substitute for private supervision and pri- 
vate control such expert and scientific superintendence as 
the danger involved demands, and, so far as public sup- 
plies are concerned, a condition of the whole may often 
be obtained far superior to any within the reach of a single 
member or family of the community. It cannot, therefore, 
be too soon or too plainly understood that common sense, 
as well as science, absolutely requires from great cities the 
most expert public supervision attainable, in place of pri- 
vate supervision surrendered. This surrender, indeed, is 
not unconditional. If public service cannot or does not 
secure or provide such adequate and expert supervision, 
there will be a return to the more primitive state. Intelli- 
gent families will prefer country to urban life, and private 
to public supervision. The rapid growth of suburban pop- 
ulations, sometimes at the expense of the more urban, may 
be already, in part at least, due to the lack of such ade- 
quate supervision in great cities. 

The most important public supplies of cities are food, 
drink and air. Of these the water supply is easily of 
the first importance to the sanitarian, for the reason that 
the air supply is as yet beyond his control, while the 
food supply, with a few exceptions, such as milk, raw 
oysters and certain fruits and vegetables, is purified by 
cookery before it is swallowed. Water, on the other hand, 
is swallowed raw, often (relatively speaking) in very large 
quantities, and it is now universally admitted that impure 
drinking water is a ready vehicle of disease. 

It is one of the immense advantages of the zymotoxic 
theory of infectious disease that it has made easy of com- 



PUBLIC SUPPLIES AS PUBLIC DANGERS 223 

prehension the precise method of conveyance of disease 
germs. At the same time it is no less valuable in other 
directions, since it makes it possible, at least for experts, 
to understand why some diseases are, and some are not, 
readily conveyed by water ; how, precisely, impurity arises ; 
how impurity may be avoided or overcome, and purity es- 
tablished ; and finally, how purity, having been once estab- 
lished, may be effectually or ineffectually conserved. When 
we consider the enormous quantities of water required by 
large cities, most of which is not used for drinking, but all 
of which must be fit to drink, 1 we may readily appreciate 
the importance of the subject with which this lecture deals. 

§ 2. — The Atmosphere as the Source of Water Supply 

The ultimate source of all water supply, public or pri- 
vate, is the atmosphere, in which the vapor of water 
(derived from land or sea) is condensed and precipitated 
as rain, snow, dew or fog. Theoretically, every rain-drop 
must form about some material particle, and the only par- 
ticles of this kind in the atmosphere are particles of dust. 
Dust particles are frequently largely composed of the 
bodies of micro-organisms, and hence it follows that at the 
very instant of its birth the rain-drop may enclose one or 
many micro-organisms. On the other hand, such bacterial 
bodies may not be alive, but dead; and dust consists of 
many other things than micro-organisms, bits of inorganic 
matter and organic, though unorganized, particles, so that 
only a few rain-drops, probably, can be conceived of as 
including micro-organisms, still less living micro-organisms, 
at the start. Again, it must not be forgotten that even if 
we assume the presence of some living micro-organisms in 

1 In the United States it has not hitherto been considered advisable to 
install two systems of water supply, one potable and one non-potable. This 
is done, however, in some cases, e.g. in Paris. See on this subject Special 
Report, Mass. State Board of Health, upon a Metropolitan Water Supply, 
p. 217. Boston, 1895. 



224 



PURITY IN PUBLIC WATER SUPPLIES 



rain-drops, these are doubtless, with the rarest exceptions, 
saphrophytic and not pathogenic. Our present knowledge 
of the behavior of pathogenic germs in the air is very 
limited, and this is particularly the case with those dis- 
eases, such as typhoid fever and Asiatic cholera, which are 
oftenest water-borne. Granting, however, the possibility 
of their presence in air, and the possible concurrence of 
soluble organic particles, it is obvious that a drop of such 
naturally distilled water may become polluted and even 
infected from its very birth. As it falls into the lower 
layers of the atmosphere, richer in dust, the chance of 
such pollution must necessarily increase pari passu. The 
possibility of such atmospheric contamination of water, 
and even its infection, must never be forgotten, but yet 
cannot be regarded, in the present state of our knowledge, 
except in very rare and unusual cases, as important. 



§ 3. — The Pollution of Rain-water and Snow by Dust 

The phenomena afforded by snow deserve especial, 
though brief, mention in this connection. A snowflake, 
especially if moist, appears to be a kind of filter through 
which a relatively large amount of air passes as the snow- 
flake falls; and this peculiarity of structure doubtless 
explains the fact that snow, particularly that first to fall, is 
often really dirty and rich in micro-organisms ; while, at the 
same time, the atmosphere after a prolonged snowfall is 
bacterially, as well as to the senses, noticeably purified. 
It follows as a matter of course that melted snow or snow 
water — and, we may add, snow ice — is far from pure; 
and that the water derived from melted snow in periods of 
" thaw " is not, as it might be supposed to be, particularly 
pure. On the contrary, the author observed on one oc- 
casion, when a sudden thaw had poured vast quantities 
of such water into the Merrimac River, the largest number 
of bacteria he ever discovered in the city water of Lowell, 



MICROBES IN RAIN-DROPS AND SNOWFLAKES 22$ 

viz., 33,000 per cubic centimetre — a number far in excess 
of that observed when the spring freshets had polluted the 
river, or in summer, when the proportion of sewage to other 
water in the river is highest. 

If, however, proof were needed that typhoid fever and 
other diarrhoea! diseases can be conveyed otherwise than 
by water supplies drawn through or over the earth, it 
would be enough to mention those places, such as Ber- 
muda, where water is obtained for drinking only from 
cisterns or cemented basins on the hills, in which rain- 
water only is collected, and where, nevertheless, typhoid 
fever is by no means unknown either among the troops or 
the citizens. It hardly needs to be added that such fever 
is probably not attributable to drinking water. 

§ 4. — Influence of the Earth upon the Purity of Rain-water 

Once the rain-drop, alone or combined with others, 
touches the surface of the earth or its appurtenances — 
such as rocks, trees, roofs, fences, haystacks, animals — it 
meets, almost immediately, abundant dust or dirt, including 
matters organic and inorganic, soluble and insoluble, living 
and lifeless. As it rolls over the dusty rock alone, or with 
others forming a trickling stream, it naturally dissolves 
some substances and sweeps on others mechanically — its 
departure from purity increasing as it proceeds. If it 
wears away the soil, enough of the latter may be carried 
along to make it discolored or even muddy, no chemical 
analysis of such water being needed to show its pollution, 
while bacterially it is charged with thousands of micro- 
organisms in every cubic centimetre. This is its horizon- 
tal or surface-displacement history. If, on the contrary, 
the rain-drop falls upon porous, absorbent earth, not already 
water-logged, it will sink by gravity, possibly also by capil- 
larity, or by the push of other particles from behind, down 
into the spongy earth. This will be a vertical displace- 



226 



PURITY IN PUBLIC WATER SUPPLIES 



ment ; and here, also, it will as a rule come into contact 
with matters organic and inorganic, soluble and insoluble, 
living and lifeless. Whether its alighting place be sand 
or soil, it will usually find the porous earthy particles 
mantled with bacterial jelly, dead or alive, wet or dry. 
And immediately actions and reactions, physical and 
chemical, will begin, and continue until a new condition 
has arisen. Water, that thus on touching the earth takes 
the vertical direction, is commonly called " ground " water ; 
while that which quickly moves off more or less horizontally 
is called " surface " water. Both, it will be observed, are 
comparatively impure when they arrive on the earth ; that 
is to say, they consist of pure water holding in solution 
and suspension certain organic and inorganic, living and 
lifeless, substances derived from the atmosphere. 

This is perhaps the best place to remark that the terms 
"pure" and "impure" are relative only. We have thus far 
used these terms in the chemical sense, yet, in the popular 
sense, rain-water is remarkably pure. We may allow the 
popular meaning and still keep in mind the fact that rain- 
water, from the chemical and bacterial point of view, is 
of relative purity only. From this point onward, it will be 
convenient if we consider separately the two great classes 
of natural waters, namely, " ground " waters and " surface " 
waters. 



§ 5. — Rain-water and the Living Earth. Ground Waters 
and their Pollution and Purification 

Rain-water on entering porous earth (either sand or soil 
open or close in texture) is at once brought under new 
conditions and into close contact with swarming bacterial 
life. The earth is the home of the bacteria. They are 
found in the air, but only because they have been lifted 
into it by winds, in the form of dried earth or dust. They 
are found in water, — in streams, lakes and the sea, — but 
seldom in density of population at all comparable to that 



RAIN AND THE LIVING EARTH 227 

existing in the surface layers of the earth. The reason for 
this seems to be that at the surface of the earth bacteria 
secure at the same time oxygen, moisture and food — the 
most favorable conditions for their life. It appears to be 
very doubtful if bacteria are preeminently aquatic. Many 
species at any rate seem to inhabit the surface layers of 
the earth, and if, as appears to be the case, they are largely 
and perhaps preferably terrestrial, this, as we shall see, is a 
matter of great consequence in the establishment and con- 
servation of the purity of waters. 

The rain-drop arriving upon the porous earth is at once 
greeted by a hungry population of bacteria mantling the 
sand grains over which it is spread ; and this, too, a perma- 
nent, not a nomadic, population. More or less slowly it 
sinks through this living, gelatinous layer, and as it passes 
on it is robbed of its suspended organic matters and of some 
of those in solution. It is also mechanically filtered to some 
extent, no doubt ; but the main thing is that as a result of 
its journey, it is so purified in respect to its organic matters 
that it can no longer support abundant bacterial life. Mean- 
while it readily dissolves the end-results and the by-products 
of the luxuriant bacterial vegetation through which it passes, 
and becomes the vehicle of nitrates, sulphates and other 
mineral matters. As it sinks lower and lower, it dissolves 
more and more of such salts, and, passing by other resident 
bacteria, is increasingly purified of organic matters capable 
of supporting bacterial life. Such water may contain bac- 
teria, but, as abundant experiments have shown, these are 
relatively few in number and singularly slow of develop- 
ment. Water derived from deep wells is generally poor in 
bacteria, and even when not poor, is characterized by cer- 
tain peculiarities which remove it from the category of 
waters charged with ordinary bacteria. In the case of most 
ground waters, a high degree of organic purity is estab- 
lished by the natural processes just described; and if such 
waters be collected in protected springs, wells, or covered 



228 



PURITY IN PUBLIC WATER SUPPLIES 



reservoirs properly constructed, their organic purity is 
readily conserved, and they constitute (in such cases) some 
of the most satisfactory water supplies known. 

There are, however, certain conditions which limit the 
usefulness of " ground " waters. In the first place, while 
of high organic purity, they may have become so rich in 
inorganic matters as to belong to the class of " hard '• 
or "mineral" waters, which, by common consent, based 
upon general experience, places them in the category of 
undesirable waters, inferior for public supplies. Far more 
important, however, is the fact that such waters are neces- 
sarily limited in quantity and, therefore, not often available 
for great cities. Obviously ground water can occupy only 
the interstices of the earth's crust, is subject when drawn 
upon to high friction, and therefore moves with slow veloc- 
ity, so that from any one point, or from a few, only a 
limited amount of water, and that at a low rate of flow, 
can safely be counted upon. Great cities, however, require 
large quantities of water, and often large quantities within 
a very short time ; so that it is easy to see why, for them, 
ground waters, will seldom, if ever, be adequate sources of 
supply. 

On the other hand, ground waters may be polluted 
instead of purified by their passage through the earth. 
If the earth is itself impure or overtaxed from leaky cess- 
pools, sink drains or other sources of foulness, natural puri- 
fication may give way to unnatural pollution. This is the 
accepted theory of the pollution of domestic wells. But, 
in view of the remarkable purifying powers of the earth, 
and the almost total lack of satisfactory evidence of disease 
arising from pollution thus effected, the author is strongly 
of the opinion that the damage done by underground pol- 
lution of domestic wells has been greatly exaggerated. 
Excepting in those rare cases of fissures in the earth which 
give easy access for pollution from the surface, and except- 
ing pollutions which have come in from the open top, he 



OBJECTIONS TO GROUND-WATER SUPPLIES 229 

is, and long has been, very sceptical concerning much of 
the damage attributed to domestic wells. It is very much 
to be feared that more harm has been done in these cases 
by throwing investigators off the true scent than by the 
pollutions themselves, real or imaginary. 

Much more serious than pollutions of the soil are the 
dangers of infection of ground waters from workmen 
within wells themselves, such as happened, for example, 
in the well-known Caterham (England) case reported 
upon by Dr. Thorne-Thorne. In this instance it ap- 
peared that the bowel discharges of an incipient or 
" walking " typhoid patient, a laborer in one of the open 
wells supplying the towns of Caterham and Red Hill, 
found direct access to the pipes, and brought on a severe 
and widespread epidemic among users of this ground-water 
supply. (For an account of this epidemic, see pp. 191- 
200.) 

§ 6. — The Conservation of Purity of Ground Waters 

Finally, ground waters have the serious defect, that in 
order to remain pure after collection, they often require to 
be kept in the dark. The cities of Newton and Brook- 
line, Mass., derive ground-water supplies of great or- 
ganic purity from driven wells in an uninhabited district 
of the Charles River valley. But in order to conserve a 
purity established by natural filtration, these cities have 
had to build costly covered reservoirs ; because on expos- 
ure to the light, such ground waters become infested with 
chlorophyl-bearing microscopical organisms (diatoms, des- 
mids, etc.), which in turn support noxious infusorial ani- 
mals, and give rise, not infrequently, to highly disagreeable 
and even nauseous tastes and odors, sometimes described 
by the consumers of the waters as resembling " cucum- 
bers," "fish-oils," "pig-pens," etc. The conservation of the 
purity of ground waters thus often becomes a matter 
requiring expert treatment. 



230 PURITY IN PUBLIC WATER SUPPLIES 

§ 7. — Surface Waters and their Pollution 

Let us now turn to that class which we have called 
"surface" waters, and have described as characterized 
by a more or less horizontal movement of their parti- 
cles after these have fallen upon the earth. In this case, 
the water which falls upon the surface, more or less impure 
from aerial pollution, instead of being subjected immediately 
to a progressive purification by sinking into the earth, moves 
along the surface of the earth, which it erodes, growing in 
volume as it proceeds, and forming rills, rivulets, or larger 
streams, — brooks, creeks, and rivers, — which still continue 
to move along the earth's surface, exposed to all sorts of 
pollution, until they pause for a longer or shorter time in 
ponds and lakes, or finally join the sea. The area over 
which this process goes on is called a " watershed," and 
much of the water which falls as rain or snow is thus shed 
off, as from a roof, without ever having soaked into the 
porous, purifying earth. 

But it would be a mistake to suppose that the entire 
volume of brooks, rivers, and lakes has been thus derived. 
The greater part, even of the so-called "surface" waters, 
except in times of freshet due to sudden thaws or to heavy 
and prolonged rain, is really ground water, purified by a 
shorter or longer passage through the porous earth. It can- 
not be too strongly emphasized that a very large portion of 
the water of all rivers, even of those most polluted, is highly 
purified ground water ; and this fact serves well to show 
how very impure the really surface-water portion of such 
streams must be. Other things equal, a water derived from 
a quick-spilling watershed must always be relatively impure 
and dangerous, because to the natural impurities of rain 
water have been added the surface impurities of the earth, 
violently detached and rapidly conveyed. 

It will be clear, therefore, at the very outset, that the 
problem of the establishment of purity of surface water is 



SOURCES OF POLLUTION OF SURFACE WATERS 23 1 

by no means easy. At first sight it would even seem that 
the larger a river is the more polluted it must be; for it 
has the longer been exposed to the manifold sources of 
pollution on its shores and from its tributaries, while as it 
flows no obvious sources of purification exist. A river to 
the casual observer seems like a great vena cava receiving 
a host of tributary veins, each of which has simply drained 
its own area; or like a cloaca^ receiving drainage from a 
thousand lesser drains. 



§ 8. — The lt Self -purification of Streams" Again 

How, then, we may well ask, did it ever happen that 
many well-regulated American cities, some of them of 
large size, have in the past drawn their water supplies 
from polluted rivers or lakes, not heedlessly, but on the 
advice of the ablest engineers and sanitarians of the day ? 
The answer is that these engineers, in common with the 
best sanitarians of the time, trusted to a theory of the 
establishment of purity in surface waters, which we now 
know to have been only a half-truth and utterly untenable ; 
namely, the theory of " self -purification " of streams. 
In substance this theory was, that " running water purifies 
itself." It was based on the obvious fact that a stream 
befouled at a certain point often shows no visible sign of 
such defilement at places some distance below. It was 
powerfully supported, however, and seemingly established 
as a law of nature, by the chemistry of the day, which 
sufficed to show, in correspondence with the evidence of 
the senses, that there was actually less organic matter at 
the lower than the higher point. Here, plainly, was 
actual scientific proof of purification — or what seemed 
to be such. Relying upon this theory, many cities — and 
some of them great cities — in America and elsewhere 
introduced water supplies from polluted streams, relying 
simply upon the self-purifying power of running water to 



232 PURITY IN PUBLIC WATER SUPPLIES 

destroy the pollutions known to be poured into the streams 
at points above (cf. p. 129). 

To-day we realize that this theory is only half true, and 
that such self-purification is only partial and absolutely 
unreliable. By a curious reversal of scientific opinion, we 
now hold that it is precisely " running " water which is 
least likely to purify itself, while stagnant (standing) water 
— formerly looked upon with dread and suspicion — is now 
in much favor. The old theory was in vogue long enough 
to enable us to make a wonderful series of experiments, 
and on a stupendous scale — experiments in which whole 
cities confidingly used for years sewage-polluted waters, 
often with sad results, yet results of lasting instruction to 
mankind. Never again, so long as civilization endures, will 
intelligent communities, acting under expert advice, need 
to repeat these sad experiments. The lesson was painful 
and costly, but it has been learned, and will never be for- 
gotten. 

The source of error in the earlier practice was in the 
neglect of the factor of dilution, with the assignment 
to true purification and actual chemical change of what 
was really for the most part dilution by ground water, 
which, as has been said above, not only forms a large pro- 
portion of the volume of most rivers, but also brings to 
them water of a high degree of organic purity. In so far 
as a mixture of pure water with foul can purify the lat- 
ter, there is truly a marked " self-purification " of rivers. 
There is even more than this in fact, for some of the 
pathogenetic elements disappear en roitte from cold, or 
inanition, or by entanglement, or by falling to the bottom, 
or by the germicidal influence of light, or from other con- 
ditions, all of which may be summed up in the words 
" unfavorable environment." But, obviously, the more 
rapid the stream, the less such conditions of whatever 
kind can act, and the more certain the damage likely to be 
done to the consumers of the water below. 






"SELF-PURIFICATION" IN STREAMS AND LAKES 233 

§ 9. — Quiet Water, not Running Water, Purifies Itself 

It is therefore not so true that "running" water, as that 
quiet water, purifies itself. We may even go so far as to 
say that the first requirement for the natural establishment 
of purity in surface waters is quiescence. But quiescence 
in rivers is ordinarily impossible. Hence the establish- 
ment and conservation of purity in rapid rivers is to-day 
regarded as, by natural means, impossible ; and no river, 
unless from an absolutely uninhabited watershed, is to be 
regarded as suitable for direct use as a public water supply. 



§ 10. — Natural Processes of Water Purification 

Fortunately there exist, nevertheless, purely natural pro- 
cesses by which the water even of polluted rivers, though 
not in the rivers themselves, can be readily purified on a 
large scale ; and it follows that such streams may become 
available, although of course never directly, as valuable 
sources of water supply, even for great cities. The time 
has forever gone by when a city or town can honestly 
pump the water of an ordinary river at its doors, without 
any previous purification, directly to its citizens. On the 
other hand, we probably understand to-day better than 
ever before the nature of the processes required to effect 
the purification which is so indispensable. In fact, we 
have abundant and positive evidence, not only from the 
data afforded by the bacteriology of natural waters, but 
also from the actual experience of cities which have used 
such waters, that there are purely natural processes 
available, which under certain conditions are capable of 
producing a high degree of purification of polluted surface 
waters. These processes are of great scientific as well as 
practical interest, and deserve our most careful, if neces- 
sarily brief, consideration. We may dwell accordingly, 
first, upon the purification effected by simple quiescence, 






234 PURITY IN PUBLIC WATER SUPPLIES 

as this is obtained in nature in lakes and ponds and as it 
can be effected, even for rivers, by artificial storage. 

A case of this first kind is that afforded by the public 
water supply of Burlington, Vt. Burlington is the only 
city in New England which derives its water supply from 
the same lake into which it empties its sewage, although 
this arrangement for water-supply and sewage disposal is 
common enough in other parts of the United States, such 
as Chicago (until 1900), Milwaukee, Duluth, Buffalo, Cleve- 
land, and in Toronto, Canada. Burlington is situated at 
the eastern extremity of a broad bay on Lake Champlain, 
and when, in 1866, the citizens determined to have an 
ample public water supply for fire and other purposes, 
they naturally turned to the lake (cf. p. 132.) 

The waterworks were built in 1867, the intake being 
located on the lake front, near the northern extremity 
of the docks. For some years the water supply gave 
entire satisfaction, and in 1870 the health officer reported 
that at no time had the city water supply held so high a 
place in the public estimation. When sewers were put in, 
the trunk sewer, carrying most of the sewage of the city, 
was made to empty into the lake about one-half mile south 
of the water intake ; and although there was gradually an 
increasing conviction, based upon the evidence drawn from 
the prevalence of diarrhoea and dysentery, with a small 
amount of typhoid fever, that things were not altogether 
satisfactory, matters did not become bad enough to cause 
the removal of the sewer outfall to a more remote point 
until 1885, when it was carried to a place one mile, 
instead of one-half mile, away from the intake of the 
waterworks. 

Meantime the city had increased in population, and the 
sewer connections with dwellings had multiplied ; but even 
as late as 1892, while strongly disapproving of the local 
conditions, and urging most emphatically a change in 
them, the author himself, after a very careful investigation, 






THE CASE OF BURLINGTON, VERMONT 235 

was forced by the facts to report to the city officials, that 
so great was the purification accomplished by this one 
mile of lake quiescence that there was no immediate 
reason for excessive anxiety or alarm for the sanitary 
condition of the water supply. He reported among other 
things that "the results show conclusively that the mor- 
tality from typhoid fever, — and the same is true for 
diarrhoea and dysentery, — has not been large in Bur- 
lington during the last twelve years. The average annual 
mortality from typhoid fever from 1870 to 1891 was 
3.57 per ten thousand inhabitants." He then went on 
to show that Burlington compared favorably in this re- 
spect with many cities having water supplies of undoubted 
purity, and stated that in respect to mortality from typhoid 
fever it had a better record than many cities having water 
supplies of good reputation. He added, that during the 
past three years he had repeatedly made bacteriological 
analyses of the Burlington supply, and had found no satis- 
factory evidence of the presence of sewage in the drinking 
water. In spite of these facts, however, he urged that the 
location of the intake of the waterworks as near as it was 
to the main sewer of the city was highly objectionable, if 
not positively dangerous, and that he regarded it as a con- 
stant menace to the sanitary welfare of the city. 

Now how had it happened that such extensive befouling 
of the lake front, only one mile, and for some years only 
one-half mile, from the intake of the drinking water of the 
city, had done so little harm ? The answer is that here, 
precisely as in many rivers which were formerly supposed 
to have purified themselves by " running " or exposure to 
free oxygen, dilution with pure water did much ; and, what 
was not true in the case of the rivers, qiiiescence did far more. 
Bacterial analyses showed that at the sewer outfall the 
numbers of bacteria were millions, and the kinds had clearly 
marked sewage characteristics. But at points one hun- 
dred feet away ninety per cent of these had disappeared, 



236 PURITY IN PUBLIC WATER SUPPLIES 

and at one thousand feet many more. At the distance of 
half a mile nearly all trace of sewage had disappeared, and 
a mile away no evidence of it could be found. It should 
not fail to be stated that in the Bay there are no regular 
currents, but only wind currents setting sometimes in one 
direction, sometimes in another; and that the amount of 
sewage poured in from a city of the size of Burlington is 
not very large, as it then had only about fifteen thousand 
inhabitants. 

Furthermore, the sewer outfall opened into a small 
pocket or basin of its own, where lively fermentation 
went on in summer; and this was an added purifying 
agency, though dwellers in the neighborhood complained 
bitterly at times of the evil smells arising from this little 
basin. The fact, however, that in this pocket the sewage 
lingered quietly for a time, and fermented more or less, was 
undoubtedly favorable to its purification. When, a year or 
two later, it was determined to do away with this basin, the 
citizens were warned of the added danger involved, and 
finally were persuaded to carry the intake pipe of their 
water works three miles out into the purer waters of the 
broad lake. 

It is certainly a remarkable and highly important fact, 
that under certain conditions a city or town — but always 
one of small size only — may safely drain into, and 
drink from, the same lake, — a condition which may be 
forcibly described as drinking from the other side of its 
own cesspool. This is, in fact, what is done by such cities 
as Duluth, Cleveland, Chicago (up to 1900), and Mil- 
waukee; but it is important to remember that it can be 
done with safety only by small communities, for the reason 
that the greater the city the nearer we come to a quick 
circulation — a river of sewage flowing out, a river of water 
flowing in, — and the danger of contamination here in- 
creases with the volumes. If it increases so far as to do 
away with sufficient quiescence, we have once more estab- 



PURIFICATION BY SLOW SAND FILTRATION 237 

lished what is essentially a stream, and running water, as 
we have seen, does not effectually purify itself — it mainly 
undergoes dilution. 

§ n. — Purification by Storage 

Conversely, if a running water such as we have in a river 
can be converted into a quiet water, — as in a reservoir, 
— just such purification as we have discovered in Burling- 
ton may result. This is, indeed, what takes place, for- 
tunately, with water derived from polluted watersheds and 
stored in huge reservoirs, — great and often adequate puri- 
fication may be established by prolonged quiescence, or 
storage. There is every reason to believe that the princi- 
ples involved in the purification which goes on in Burling- 
ton are typical in whole or in part of many other similar 
cases. Some bacteria perish almost immediately in the 
cold water of the lake ; some settle to the bottom and per- 
ish there ; some are killed by light as they float on the 
surface ; some are devoured by predatory infusoria ; the 
more hardy survive, perhaps, but do not multiply because 
of lack of food and other unfavoring conditions, and so 
are simply scattered by dilution ; until finally only those 
remain which can permanently thrive in the now relatively 
pure water ; and these are apparently mostly harmless. 

§ 12. — Purification by Slow Sand Filtration 

It follows as a matter of course, from what has now been 
said, that if a city or town must use a river as its source 
of supply, it must ordinarily first purify it either by natu- 
ral or by artificial means. One of the natural processes 
available has just been described, and may be summarily 
characterized as quiescence effected by prolonged "stor- 
age." Another process may be defined as " natural filtra- 
tion." Thanks to the labors of the State Board of Health 
of Massachusetts, and to the intelligence of the people of 



238 PURITY IN PUBLIC WATER SUPPLIES 

that State who have supplied the necessary funds to carry- 
on what was perhaps the most elaborate and costly series of 
experiments hitherto undertaken in the interests of sanitary 
science, we are to-day in full possession of the data which 
enable us to define with certainty the natural laws govern- 
ing the artificial purification of surface waters by simple 
sand filtration. These are now a matter of common knowl- 
edge among experts, and therefore need not be dwelt upon 
at length at this point. Stated in a few words, we may 
say that the process of purification by " natural filtration " 
is accomplished precisely as is the case with the rain fall- 
ing on porous earth (p. 226). 

Land of porous texture is first prepared, sand having 
been found preferable for the purpose, while in the best 
practice specially constructed "areas" or "beds" of sand 
are made and then thoroughly underdrained, so as to facili- 
tate the collection of the purified water. The water to be 
filtered is allowed to run over the surface and find its way 
down through the open, porous sand. Very soon, however, 
bacteria take up their residence on the sand grains, especially 
near the top, bacterial jelly accumulates, and a purifying 
mechanism or organism of great efficiency results. If this 
mechanism be operated intermittently, air passes into the 
interstices of the sand, precisely as into ordinary earth, 
only more freely; and some of the organic matters are 
removed by nitrification, that is, by complete conversion 
into mineral matter. In this case, also, the bacterial jelly 
forms, but farther down in the sand, and makes an effective 
purifying medium. 

Innumerable tests of such mechanisms as this have been 
made and their high efficiency shown. They are usually 
called sand "filters," but the name is unfortunate as imply- 
ing something artificial rather than natural. The process 
is, in fact, nearly if not exactly the same as in the purifying 
of surface waters which pass through earth and become 
ground waters; although by selecting the porous materials, 



PURIFICATION BY MECHANICAL FILTRATION 239 

" hardness " and some other faults of ground water are 
avoided. It is by such means that London, Hamburg, 
Berlin, and Lawrence in Massachusetts, secure from pol- 
luted surface waters satisfactory and sanitary supplies. 
Albany has followed in their footsteps, and Washington, 
Philadelphia and many other American cities must prob- 
ably do likewise. For the establishment of purity in sur- 
face waters, we have, then, two important and natural 
processes, — " storage " and " sand filtration." 

§ 13. — Artificial Processes of Purification of Water Supplies 

Various attempts have been made to substitute artificial 
for natural processes of purification of water supplies, and, 
under certain circumstances, there can be no question of 
the importance or value of these procedures. The only 
processes of this character thus far seriously proposed are 
those known in America as processes of " mechanical " 
filtration, for which the advantages are claimed of, first, 
rapidity ; second, hygienic efficiency ; third, removal of 
clayey turbidities and thorough decolorization ; fourth, con- 
venience of installation ; fifth, cheapness. The principles 
involved in mechanical filtration are comparatively simple, 
being substantially as follows : a chemical reagent of pre- 
sumably harmless character, such as alumina, is added in 
a certain small proportion to the water to be purified, yet 
sufficient to produce, if the reaction of the water be right, 
a flocculent precipitate. If the water were kept quiet and 
allowed to stand, this precipitate would entangle and carry 
to the bottom a large amount of the suspended matters 
present, including the bacteria. In fact, however, this is not 
found to be necessary, but after the addition of the coagu- 
lant the water is rapidly passed through a sand filter upon 
the surface of which the flocculent precipitate mentioned 
quickly collects and forms a layer. This more or less ef- 
fectually detains suspended matters, including the bacte- 



240 PURITY IN PUBLIC WATER SUPPLIES 

ria, and removes from the water a large amount of any 
color which it may contain. Mechanical appliances, such 
as the reversal of the stream, allow for the washing of the 
sand niters and for the repetition of the process, which 
may obviously be carried on rapidly and therefore upon a 
comparatively small area. 

§ 14. — Hygienic Efficiency of Rapid Mechanical Filters 

Tests of the hygienic efficiency of rapid mechanical fil- 
ters were formerly, for the most part, wanting, but experi- 
ments made on the water of the Ohio River at Louisville, 
Ky., and Cincinnati, O., and upon one of its tributaries, 
the Allegheny River at Pittsburgh, Penn., have shed much 
light upon the subject. 1 

§ 15. — Conservation of Purity in Surface Waters 

Enough has been said to show that the natural establish- 
ment of purity in water supplies is a process somewhat 
elaborate and complicated. The conservation of the purity 
of ground waters, when once they have been collected, 
has already been shown to be a matter requiring intelli- 
gent supervision (p. 229). The same thing is equally true 
of surface waters, especially those required for great cities. 
If, after collection, these waters are stored in huge reser- 
voirs rich in organic matter (as is usually the case), they 
not infrequently become infested with microscopical organ- 
isms which generate in them disagreeable, and sometimes 
even nauseous, tastes and odors, of which the consumers 
bitterly and very properly complain. The supply of New 

1 Reports have appeared upon all of these experiments, namely, upon the 
purification of the Ohio River at Louisville and at Cincinnati, by George W. 
Fuller, on behalf of the Water Departments of these cities, respectively, and 
at Pittsburgh by Allen Hazen on behalf of the Filtration Commission of the 
city of Pittsburgh. Those interested in the details of this subject are referred 
to these reports. 



PURIFICATION OF RESERVOIRS BY " STRIPPING " 241 

York City is collected from watersheds by no means 
uninhabited, and is in many respects well purified by 
storage. Until very recently, however, it has not been 
thought necessary, even if it is to-day, in New York, to 
remove all possible organic matter from the storage basins 
or reservoirs employed. 

The latest and best practice, however, is exemplified by 
the great Metropolitan supply for Boston and the twenty- 
eight cities and towns in its immediate vicinity. There 
the large Wachusett reservoir, which alone is to cost 
$9,000,000, is now (in 1901) being carefully prepared, by 
the removal of all peat, muck, stumps, loam, and other 
organic matter, from the sides and bottom of the reservoir, 
in order that organic matters may be lacking for the sup- 
port of these same microscopical organisms during storage. 
For this specific purpose of "stripping," as it is called, it 
is estimated that $3,500,000 will be spent. In this case, 
which probably represents the most advanced ideas in the 
establishment and conservation of purity in surface waters, 
great pains are being taken : — 

1st. To secure water originally of high organic purity. 

2d. To keep the watersheds as uninhabited as possible. 

3d. To purify the water collected, by long storage in an 
immense reservoir ; and, 

4th. To conserve its purity, when this has once been 
established, by having the reservoir at the start as free as 
possible from organic matters which might support bacteria 
or microscopical organisms. 

§ 16. — Recapitulation 

We may point out briefly, in review, the practical appli- 
cation of the principles now laid down, to the water sup- 
plies of great cities, which, as has been shown, must, for 
the most part, be surface waters. The aerial pollutions, if 
any, may be neglected, because beyond our control. But 



242 



PURITY IN PUBLIC WATER SUPPLIES 






with the principal source of pollution, the watershed, it is 
quite otherwise. Obviously the watershed largely deter- 
mines the character of the surface water. The water- 
shed may be uninhabited, or thickly or thinly inhabited. 
It may consist of swampy, peaty or manured soils ; or 
of forests, rocks and barren slopes ; or of a combina- 
tion of such things ; and upon these conditions will 
depend largely the character, purity and conservation 
capacity of the water collected. It is rarely the case 
that a great city can secure for its water supply a totally 
uninhabited watershed, or one free from swamps or other 
accumulations of organic matter. Where a choice is pos- 
sible, it should as far as practicable do this. In the ideal 
system of surface-water supply, the city should own the 
entire watershed, and keep it clean and uninhabited. But 
if, as will usually be the case, the watershed is more 
or less inhabited and swampy, pains must be taken to 
guard against specific pollutions from habitations, and to 
drain swamps, so as to collect the rainfall from the for- 
mer as slowly, and from the latter as quickly, as possible. 
For all the details of these matters, the most intelligent 
and educated sanitary supervision are required. This is 
the place for young sanitary engineers who, as careful 
scientific inspectors, should be employed, not occasionally 
or spasmodically, but regularly and permanently, to guard 
the sanitary condition of watersheds. To bring about 
even the possibility of this, special legislation may be 
necessary, as for example was found to be the case in 
Massachusetts, where formerly the law did not allow any 
city or town, or any sanitary authority on their complaint, 
to abate nuisances or remove sources of pollution upon 
any part of the watershed from which it derived its drink- 
ing water. Afterward a statute was enacted, making it 
possible, by due process of law, for the State Board of 
Health (on complaint) to remove sources of pollution 
" within the distance of one hundred feet of the high-water 



INTELLIGENT SUPERVISION INDISPENSABLE 243 

mark of any stream or pond, or any stream, pond, spring, 
or water-course tributary thereto, polluting or tending to 
pollute such stream, pond, spring, or water-course." 

§ 1 7. — Protection of Purity of Inland Waters in 
Mas sack usetts 

The progress of legislation toward the better control, or 
sanitary protection, of watersheds is interesting and instruc- 
tive, as it is laid down, for example, in the Massachusetts 
statutes. 1 

Previous to 1878 there was apparently in Massachusetts 
no attempt to guard against pollution of public water 
supplies, still less of the watersheds from which they 
were derived ; but in that year it was made illegal to 
discharge into any stream or pond used as a source of 
water supply polluting material within twenty miles above 
the point where the supply was taken. We see here em- 
bodied in legislation the influence of the old theory of 
" self -purification " — twenty miles having been formerly 
regarded as an ample distance within which a stream 
might purify itself. 

In 1879 it was made illegal to deposit excrement or foul 
or decaying matter in any water used for domestic water 
supply on or upon the shore thereof within five rods of 
the water ; but it was also specially provided that this act 
should not be construed to interfere with the putting in of 
the sewage of a city, town or public institution, or to 
prevent boating, bathing or fishing, or the enriching of 
land for agricultural purposes. 

It was not until 1890 that any legislation of a thoroughly 
modern sort, in harmony with the sanitary science of the 
day, was enacted, and this was of the limited description 

1 The English Public Health Act of 1875 took very advanced ground on 
this subject, and was doubtless the model after which much of the Massa- 
chusetts law was shaped. 



244 PURITY IN PUBLIC WATER SUPPLIES 

already referred to, inasmuch as it restricted the powers 
of the State Board of Health, as a sanitary authority to be 
appealed to, to the limit of one hundred feet from the high- 
water mark of any stream or pond, or any tributary of the 
same. This was, of course, a distinct advance ; but with 
the inauguration of the Metropolitan Water Supply for 
Boston and vicinity, special legislation was secured for that 
area, which provided absolute control by the State Board of 
Health over the sanitary condition of the entire watersheds 
which it was proposed to use. 

§ 1 8. — Sanitary Protection of Public Water Supplies 

In Chapter 488 of the Acts of the General Assembly of 
Massachusetts for the year 1895, to provide for a Metro- 
politan Water Supply, an advanced position was taken in 
regard to the sanitary protection of water in Massachusetts 
in the following sections : — 

SANITARY PROTECTION OF WATER 

Section 24. The State Board of Health is hereby authorized and 
required to make rules and regulations for the sanitary protection of all 
waters used by the Metropolitan Water Board for the water supply of 
any city, town, or water company aforesaid. . . . 

ENFORCEMENT 

Section 27. Said Metropolitan Water Board and their employees 
designated for the purpose shall enforce the provisions of this act, and 
of the rules, regulations, and orders made thereunder, and may enter into 
any building, and upon any land, for the purpose of ascertaining whether 
sources of pollution there exist, and whether the provisions of this act 
and of the rules, regulations, and orders made as aforesaid are complied 
with. . . . 

In 1897 what was practically the same authority was 
granted to the State Board of Health, covering all water- 
sheds within the state of Massachusetts tributary to public 
water supplies, in the shape of an act, Chapter 510, Acts of 






PROTECTION OF PURITY BY LEGISLATION 245 

1897, which reads as follows, and probably represents, as 
nearly as can be expected in conservative legislation, the 
best ideas of the sanitary science of to-day on this subject. 



ACTS OF 1897. CHAPTER 510 
An Act relative to the Pollution of Sources of Water Supply 

Be it enacted, etc., as follows : — 

Section i. The State Board of Health shall have the general 
supervision of, and have authority, from time to time, as it may deem 
expedient, to examine all streams and ponds used by any city, town, or 
water or ice company in this Commonwealth as sources of water supply, 
together with all springs, streams, and water sources tributary thereto, 
with reference to their purity, and shall have authority to make rules, 
regulations, and orders for the purpose of preventing the pollution, and 
securing the sanitary protection of the same. 

Section 2. Said Board shall appoint such agents and servants as 
it may deem necessary, who shall attend to the enforcement of the pro- 
visions of this act and of the rules, regulations, and orders thereunder, 
and shall have the power, by such agents and servants as aforesaid, to 
enter into and upon any building structure and premises for the purpose 
of ascertaining whether or not any sources of pollution or danger to the 
water supply there exist, and whether or not the provisions of this act 
and the rules, regulations, and orders made as aforesaid are complied 
with and obeyed. . . . 

Section 3. Upon complaint to said State Board of Health by the 
mayor of a city or the selectmen of a town, or by a board of water com- 
missioners, or by the president of a water or ice company, that manure, 
excrement, garbage, sewage, or any other matter is so deposited, kept or 
discharged as to pollute or tend to pollute the waters of any stream, 
pond, spring, or water-course used by a city, town, water or ice company 
as a source of water supply, or that any other cause of pollution to such 
water supplies exists, the said Board of Health shall appoint a time and 
place for hearing parties to be affected, and give due notice thereof to 
such parties ; and after such hearing, if in its judgment the public 
health requires it, shall prohibit the deposit, keeping, or discharge of 
any such material, or other cause of pollution as aforesaid, and shall 
order any person to desist therefrom and to remove any such material 
theretofore deposited, or other cause of pollution ; but said Board shall 
not prohibit the cultivation and use of the soil in the ordinary methods 



246 PURITY IN PUBLIC WATER SUPPLIES 

of agriculture, provided that no human excrement is used thereon. But 
said Board shall not prohibit the use of any structure which was in 
existence at the time of the passage of this act, in case the complaint 
referring to or including such structure is made by the board of water 
commissioners of any city or town, or by any water or ice company, 
unless the board of water commissioners or the water or ice company 
making the complaint shall file with the said State Board of Health an 
order or vote of its city council, selectmen, or water or ice company 
respectively, to the effect that such city, town, or water or ice com- 
pany will, at its own expense, make such changes in said structure or 
its location as said Board shall deem expedient. Such order or vote 
shall be binding on such city, town, or water or ice company ; and, 
when such changes shall have been made, all damages occasioned 
thereby shall be paid by such city, town, or water or ice company ; and 
if the parties cannot agree thereon, such damages shall be determined 
by a jury on petition of either party, filed in the clerk's office of the 
superior court in the county where the premises are located, in the 
manner provided by law in relation to determining the damages occa- 
sioned by taking land for highways in such city or town, or in the case 
of a water or ice company, in the city or town in which the said struc- 
ture is located. . . . 

Section 6. Whoever does any of the acts herein prohibited or 
violates or refuses to comply with any rule, regulation, or order made 
under the authority of this act shall be punished for each offence by a 
fine not exceeding five hundred dollars, to be paid to the Commonwealth, 
or by imprisonment not exceeding one year in the House of Correction, 
or by both such fine and imprisonment. 

This law was secured only after it had been found that, 
under previous legislation which had established a hun- 
dred-foot limit, it was quite impossible adequately to protect 
Massachusetts watersheds from pollution. 



§ 19. — Sanitary Protection and Inspection of Watersheds 

Of late years it has been also learned, at least in Mas- 
sachusetts, that serious pollutions, similar to that which 
affected the ground-water supply of Caterham, England 
(p. 191), may occur in surface supplies from the temporary 
residence on the watershed of thousands of laborers, some 
of whom may be walking cases of infectious disease. Two 






SANITARY PROTECTION OF WATERSHEDS 247 

examples of this kind have occurred within the author's 
experience. 

The first happened in 1894, while a new reservoir of 
great size was under construction for a large and important 
American city. When finished it was to be connected with 
and added to an existing system of reservoirs, and during 
the work of stripping off the loam and building the dam 
large gangs of men were, of necessity, employed. The 
stream which was to be dammed naturally ran through the 
valley where these men worked, and on into the lower 
reservoirs, constituting the then existing supply of the city. 

An epidemic of typhoid fever broke out among the labor- 
ers. The author was called in to study the cause of the 
typhoid fever, but very soon saw that, valuable as such 
study might be from the aetiological point of view, the 
possible effects of the epidemic were practically far more 
important and pressing. He was sent to find the cause of 
the typhoid fever ; but this question had to wait, as soon 
as he saw the true state of affairs, while he tried to prevent 
the typhoid germs produced by the people who were work- 
ing on the brook, and using it as their sewer, from reaching 
the consumers of the water below. There were hundreds 
of men at work, and a large number of them were suffering 
with typhoid fever. All were living or working about or 
very near the brook. Many were visibly using it as a drain 
and a defecating place, and were defiling its shores at 
various points from which material during a sudden shower 
was readily washed into the brook and conveyed to a reser- 
voir below. Fortunately the system of reservoirs allowed 
this one to be disconnected for a time. The purifying 
effects of quiescence and storage were called in. The 
watershed was cleaned up, disinfection was employed, and 
every possible precaution taken to prevent further trouble. 
It is pleasant to be able to record the fact that the efforts 
of those concerned were entirely successful. 

The other case was very similar. Another large city was 



248 PURITY IN PUBLIC WATER SUPPLIES 

building a huge storage reservoir. Two thousand laborers 
were employed and lived upon the watershed, close to the 
stream which was to be dammed up. Typhoid fever broke 
out among them. They were very ignorant, and even when 
closely watched persisted in washing their soiled clothing in 
the brook which ran down into the city supply below. Ex- 
traordinary pains had to be taken to make sure that the 
purity of this infected supply was reestablished and con- 
served before it was delivered to the consumers. The chief 
responsibility in this case, also, fell upon the author, who 
was fortunately successful in his efforts to prevent infec- 
tion from reaching the users of the water. 

Still another lately recognized source of pollution of 
watersheds is their use for picnic purposes and summer 
resorts. In 1896 the attention of the State Board of 
Health of Massachusetts was called to this subject, and 
the author had the privilege of supervising a general in- 
vestigation of the sanitary condition of all the picnic and 
summer resorts of the state, but especially those located 
on the watersheds of public water supplies, with a view to 
learning the character and extent of the pollutions, if any. 
The results showed that in many cases dangerous pollutions 
existed upon the watersheds, seriously imperilling the pu- 
rity of the supplies with which they were connected. In the 
following year the work was repeated, with equally satis- 
factory results. The development of electric street railway 
systems has, in Massachusetts at least, caused many new 
''resorts" to spring up in out-of-the-way places (often 
chosen largely because of their isolation and wildness), 
and in not a few cases on or near lakes and reservoirs used 
for water supplies, or upon their watersheds. 

Far more serious, of course, are those instances in which 
villages or towns are situated within or upon a watershed. 
These cases often require the most careful study and super- 
vision. Sometimes it is necessary and possible to divert 
their drainage from the watershed ; sometimes, when this is 



SANITARY SUPERVISION OF WATERSHEDS 249 

impracticable, it can be purified on a sewage farm within 
the watershed ; sometimes other procedures are required. 
Here again intelligent supervision and control are required, 
which must be permanent, inasmuch as the conditions on 
the watershed are subject to frequent and often unexpected 
change. Few American cities, if any, have to-day such 
supervision as the standards of modern science demand. It 
is not enough to burn occasionally a few barns or to pur- 
chase and remove a few pig-pens on the watershed. The 
problem is larger than this, and requires thoughtful, en- 
lightened and continuous public service for its proper 
amelioration. 

After the careful collection of the water from the water- 
shed, it should be subjected to one or the other, or both, of 
the two great methods of natural purification — storage 
or filtration — in order to correct whatever defects it may 
still possess. If it be a ground water, further filtration is 
generally needless, but its storage must be effected in the 
absence of light. If it be a surface water, it should without 
question be stored for a time and, when possible, in well- 
stripped reservoirs, i.e. in reservoirs freed from organic 
matters. 

A wise writer, it will be remembered, has recommended 
" old books to read, old wine to drink, old wood to burn." 
It has since been discovered, in addition, that old water is 
better than new. It is said that the old-time sea captains 
seldom allowed any water to be used on board ship that 
had not been in the casks for months. The theory was 
that water, like wine, underwent a "working" or fermenta- 
tion which improved its salubrity. We now know that 
they were right, and, better, we know why : it was simply 
that harmful bacteria were given ample time to die out. 

If a surface water is known to be much polluted when 
collected, the more difficult and more heroic treatment of 
filtration should be invoked. Here again, in any particular 
case, experience and judgment are required. London 






250 PURITY IN PUBLIC WATER SUPPLIES 

first stores and then filters, with excellent results. Ham- 
burg does the reverse, and so does Lawrence, and when 
practicable, storage, both before and after filtration, is 
probably desirable and useful. 

§ 20. — Expert Supervision an Absolute Requirement 
of Modern Sanitation 

The keynote of public service is expert supervision. 
With this remark we return to the point from which we 
started. If a public supply is to be made a public bless- 
ing, it must be scientifically and skilfully, as well as eco- 
nomically, administered. It will not do to leave to the 
shifty devices of petty politicians matters like water sup- 
ply, gas supply, and food supply, which require, for mere 
public safety, skilled and highly paid supervision. If 
democratic government is to endure and to exemplify a 
form of civilization above that of the republics of Central 
America, in which plunder and bad government are the 
rule, the people must see to it that in the place of small 
politicians to manage these things, they have educated pub- 
lic servants ; instead of neglecting to care for watersheds, 
these must be supervised by men technically trained ; and 
instead of bosses and heelers to deal with these problems 
in their larger aspects, there must be faithful and able 
experts. Only on this condition can we afford to surrender 
private supervision of some of the principal avenues of our 
well-being for public supervision ; and until the most expert 
public supervision attainable takes the place of private 
control, it will remain true that a public supply is a public 
danger. (Cf. p. 221.) 



CHAPTER X 

ON ICE AS A VEHICLE OF INFECTIOUS DISEASE. THE POL- 
LUTION OF ICE. ICE SUPPLY AND THE PUBLIC HEALTH l 

§ I . — The Mingling of Melted Ice with Food and Drink 

The almost universal American custom (now rapidly 
spreading in Europe) of cooling certain drinks — such as 
water, lemonade and tea — by adding to them lumps of ice, 
which are allowed to melt and mingle with liquid to be 
swallowed, early attracted the attention of sanitarians, to 
whom the idea naturally occurred that if the ice thus added 
be impure, serious consequences may result. The amount of 
ice consumed in this way in America alone during the warm 
season, and indeed all the year round, is simply enormous. 
It is the almost invariable rule in hotels and restaurants 
to begin the service of a guest at table by filling his glass 
with broken pieces of ice or " cracked " ice, and at least 
one observer of American life and manners has cleverly 
commented upon this almost national habit. 2 In some 
clubs and hotels drinking water is put upon the table 
in the shape of glass water-bottles (carafes), in which the 
water has been frozen solid, filling the bottle with one 
solid mass of ice. This gradually melts during the meal, 
and the water which is poured from it for drinking in this 

1 This subject is treated at much length, and with full references to the 
literature, in a paper by the author and C.-E. A. Winslow, S. M., shortly to be 
published in the Memoirs of the American Academy of Arts and Sciences, in 
Boston. Frequent extracts from this paper are made in the present chapter. 

2 . . . " Ice-water, the musical tinkling of which in the corridors is the 
most characteristic sound of the American caravanserai." — J. F. Muirhead, 
"The Land of Contrasts," Boston, 1898. 

251 



252 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

case comes wholly from melted ice. Pleasure parties, ex- 
cursion parties, and the like often make use of large tubs 
of drink (water, lemonade, etc.), into which a cake of ice is 
put bodily ; and this, in melting, not only cools the sur- 
rounding liquid, but contributes to it whatever impurities it 
may contain. Raw oysters (removed from the shell) are 
sometimes placed upon a luncheon or dinner table in a 
cubical cavity, cut into the top of a large block of ice, and 
are later served with more or less of the meltings of the 
sides and bottom of the ice-cavity in which they lie. It is 
plain that if the germs of infectious disease or other impu- 
rities can survive in ice, this when melted may form a ready 
vehicle for the distribution of disease. 



§ 2. — Does Polluted Water purify itself in Freezing ? 

It is a popular belief that, at least in many cases, the ice 
which forms upon a body of water is purer than the water 
itself. This belief is probably based in part upon the well- 
known fact that when a substance crystallizes out of a 
liquid the crystals formed are usually purer than the 
mother-liquor from which they come ; and general reliance 
seems to have been placed (in America) upon this tendency 
to purification to which ice crystals also might be expected 
to be subject, until, in 1887, careful investigations by Prud- 
den showed that bacteria are not wholly eliminated from 
ice in the freezing of water, and that these may even sur- 
vive in ice for long periods. It was then remarked that 
ice often contains visible impurities, and if these, why not 
also others invisible ? 

A little reflection will show that the question of elimina- 
tion of impurities such as bacteria, which are really sus- 
pended particles, depends for its solution upon a variety of 
conditions. If, for example, the body of water, e.g. a small 
lake or pond, containing bacteria be frozen absolutely solid, 
as in the case of the carafes of drinking water mentioned 



PARTIAL PURIFICATION OF WATER BY FREEZING 253 

above, there is no reason to expect elimination during crys- 
tallization, for there is no place into which the bacteria can 
be extruded by the growing crystals. But if the ice in 
question is formed on the surface of a quiet lake or pond, 
the very first skimming of crystals produces absolute quies- 
cence in the underlying layers of water, and gravity must 
then exert a powerful effect upon the floating bacteria. 
In this case there is abundant opportunity for the elimina- 
tion of foreign particles by the growing crystals ; and as 
these gradually extend downward, they will naturally first 
invade those layers of water nearest to themselves, which, 
for obvious reasons, may be the freest from bacteria, while 
the lower layers of the pond will contain not only the bac- 
teria belonging to themselves, but also such as have been 
dragged down by gravity from the upper layers. Accord- 
ingly, the uppermost layer of such ice will often be the 
richest in bacteria ; while the next lower ice layers, espe- 
cially if their formation has been slow, may be relatively 
free from bacteria. 

Again, to take another case : If, as is often done, the har- 
vesters, after a few inches of ice have been formed, cut 
holes in the ice-sheet, allowing the subnatant water to over- 
flow it, and by freezing solidly from above to become added 
bodily to that already formed, the conditions in the case 
of this added layer will be similar to those in the carafe. 
The mass will be frozen as a whole, and no mechanical 
elimination during crystallization can reasonably be ex- 
pected. Lastly, if, after the ice has begun to form, snow 
falls upon it, and this, by a rainfall or a thaw followed by 
freezing weather, becomes added as a superficial layer of 
"snow-ice" to that upon which it fell, such "snow-ice" 
may be expected, from what has been said above (p. 224) 
in regard to the action of snow as an atmospheric filter, to 
contain large numbers of bacteria. 

From these various considerations we may conclude that 
the answer to the question, Does water purify itself in 



254 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

freezing ? depends largely upon the conditions under 
which it is frozen. If ice is formed upon a quiet lake 
or pond of considerable depth, the water of the pond 
probably does purify itself to a marked degree in freez- 
ing. But if, on the other hand, the freezing takes place 
in such a way that sedimentation has little influence, or if 
an entire mass of water is frozen solid, purification may be 
much less marked, or even largely wanting. 1 

§ 3. — Epidemics attributed to Infected Ice 

In spite of the fact that ice may contain very consider- 
able numbers of bacteria, and that it has been hitherto 
regarded as a dangerous vehicle of disease, only a surpris- 
ingly small number of epidemics have been charged to 
infected ice ; and a careful examination of the reports of 
these leaves upon the student the impression that the dan- 
gers of polluted ice have probably been exaggerated. 

The first epidemic attributed to infected ice, and care- 
fully investigated, occurred at a summer resort known as 
Rye Beach, New Hampshire, in 1875. The illness in 
question — a severe intestinal disorder — was confined to 
the guests of one of the large hotels. The milk supply, 
the water supply, and the drainage appeared to be above 
suspicion ; but the ice supply had been derived from a 
small pond, the waters of which were rendered very foul by 
a mass of putrescent matter composed of a mixture of marsh 
mud and decomposing sawdust. Chemical analysis of the 
water from the pond and of the ice showed the presence 
of high total organic matter and high ammonias, both free 
and albuminoid. The inference was that the disease had 
somehow come from the ice. In 1878 Dr. Charles Smart, 
surgeon United States Army, attributed certain cases of 

1 See Thirty-second Annual Report of the State Board of Health of Massa- 
chusetts for 1900, pp. 510, et seq. Boston, 1 90 1. Twenty-first Report (for 
1889), p. 145, et seq. Boston, 1890. 



ILLNESS CHARGED TO IMPURE ICE 255 

"malarial remittent" fever in a Rocky Mountain army 
post to the contamination of mountain streams by melting 
snow. In 1879 an outbreak of dysentery occurred in Con- 
necticut in a family of eleven persons residing in a farm- 
house. There were in all eight cases of disease, of which 
three proved fatal. This epidemic was charged to ice 
which had been cut on a small stream used as a running- 
place for pigs. In 1882 a single case of typhoid fever 
charged to ice occurred in the same state. The patient 
lived otherwise under excellent sanitary conditions, but was 
much addicted to iced water, of which he consumed large 
quantities, the ice having come from a pond into which 
drains from some laborers' houses emptied. In these 
houses there had been three cases of typhoid fever during 
the previous summer. Excepting the Rye Beach epidemic 
already mentioned, the most notable epidemic of disease 
connected with frozen water (snow) is that of typhoid fever 
in Plymouth, Penn., in 1885 (cf. pp. 200-206). In this case 
the epidemic, which was of very large proportions, was 
clearly traced to the pollution of the public water supply 
by the dejecta of a single patient suffering from typhoid 
fever. Moreover, these dejecta had been thrown, without 
disinfection, upon the snow which covered the ground near 
the house in which the patient lay ill, and had, in part at 
least, probably been thoroughly frozen. When finally the 
mass was melted by the arrival of warmer weather, and had 
been washed by rains into the public water supply, a very 
extensive and serious epidemic ensued. It appears, how- 
ever, that while the earlier dejecta were thus almost certainly 
exposed to a very low air temperature, the same cannot 
be said of the excreta thrown out just before the " thaw " 
occurred ; so that it is by no means certain that all were 
exposed to a freezing temperature. Besides, faecal mat- 
ters frozen solidly en masse are very unlike ice, properly 
so called, or such as is used for public ice supply, and the 
former might easily be a much more favorable medium for 



256 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

the viability of microbes than the latter. Accordingly, 
even if we allow that the Plymouth epidemic was caused 
by germs which had resisted very low temperatures, it 
would not by any means follow that ice as ordinarily made 
and used is an important vehicle of disease. 

Owing to the hitherto limited use in Europe of ice for 
cooling drinks, we should not expect to find on record many 
European epidemics charged to infected ice. The only one 
which need be cited here occurred at the military post 
of Rennes in 1895. Eight lieutenants of a regiment fell 
ill of typhoid fever between December 12 and 25. The 
fact that these officers did not ordinarily live in common, 
but had all attended a regimental banquet on December 4, 
pointed to something taken at that time as the vehicle of 
infection. The officers of higher rank, among whom no 
disease appeared, dined in a separate room and used for 
water only the town supply, which was excellent. The 
lieutenants on the other hand shared a " tisane" of cham- 
pagne which they mixed with chilled water. It was sup- 
posed at first that this water was derived from the town 
supply, but afterward that it came from the melting of the 
ice used for general refrigeration ; and this ice was believed 
to be highly polluted. The menu of the various classes of 
officers was the same, and certain of the petty officers who 
did not share the " tisane," but drank beer instead, were 
not attacked. 

Reviewing the evidence, it seems probable that certain 
intestinal disorders caused by decomposing organic mat- 
ters, if not by the more well-defined pathogenic germs, 
have at times been caused by polluted ice. The Rye 
Beach epidemic was carefully studied, and points directly 
to this conclusion. On the other hand, we have not been 
able to find much satisfactory evidence that typhoid fever 
or other well-known infectious diseases are carried in this 
way ; but the possibility that some obscure " sporadic " cases 
are due to infected ice, cannot be denied. 



ILLNESS CAUSED BY IMPURE ICE 257 

§4. — Investigations of the Purity of Ice by Various 
Observers 

As early as 1871 Professor Burdon-Sanderson observed 
that (liquid) culture media showed bacterial growth when 
inoculated with melted snow or ice. Von Frisch froze 
putrefying solutions, subjected the frozen mass to a tem- 
perature of —8?° C. and after the lapse of some hours 
found that sterilization had not been effected. 

Professor Joseph Leidy in 1884 exhibited at a meeting of 
the Academy of Natural Sciences of Philadelphia water de- 
rived from melted ice containing not only living infusoria 
but also rotifers and other worms. Pictet and Young sub- 
jected various species of bacteria to a temperature below 
— 70 C. for 108 hours (during 20 hours below — 130 C). 
After this treatment the cultures of B. anthracis and the 
bacillus of symptomatic anthrax were alive and virulent. 
Kowalski analyzed 60 specimens of natural ice and obtained 
from 10 to 1000 colonies per cubic centimetre, no specimen 
being sterile. Schmelk studied the bacterial life in the snow 
(and ice) of a Norwegian glacier and in the cold streams 
flowing from it. Bujwid found 21,000 bacteria per cubic 
centimeter in a melted hailstone, and similar though 
smaller figures have been obtained by others (Foutin, 
Abbott). Heyrothin 1 888-1 889 obtained in the ice supply 
of Berlin from 2 to 133,000 bacteria per cubic centimetre, 
the highest figures corresponding to chemical analyses 
which showed the most marked pollution. Prudden in 
1887 found in the natural ice supplied to New York City 
a wide variation in numbers. Many other observers have 
come to similar conclusions. 

The author and his assistants in an extended investiga- 
tion of the ice supplies of Massachusetts (see Report of the 
Massachusetts State Board of Health for 1889) found in 
the natural ice of that state (which is mostly obtained from 
ponds, lakes and rivers) very few living bacteria in the 



258 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

clear ice of the upper layers, but considerable numbers in 
some cases in the lower layers and in the " bubbly " or 
" snow " ice. An examination of the artificial ice made 
in Massachusetts in 1892 proved the number of bacteria 
to be " insignificant under the prevailing methods of manu- 
facture." (T. M. Drown, Twenty-fourth Annual Report 
State Board of Health of Massachusetts (for 1892), p. 598.) 
It appears to be certain, therefore, that cold, even when 
extreme, cannot be depended on to kill all bacteria whether 
pathogenic or saprophytic ; and both natural and artificial 
ice may, and generally do, contain more or less living 
micro-organisms. 

§ 5. — Ice as a Vehicle of Disease 

It is plain from what has been said in the last paragraph 
that ice may contain living pathogenic germs. It may 
therefore unquestionably be an important vehicle of disease. 
On the other hand, the literature of the subject fails to 
reveal any very clear evidence that it has been hitherto a 
vehicle of any great importance, while it is an indubitable 
fact that certain cities which have used ice cut from sources 
known to be infected with the germs of typhoid fever have 
not suffered perceptibly from that cause. According to 
Prudden, the ice supply of New York City was, in 1888, 
largely derived from the Hudson River — a stream highly 
polluted by the sewage of Albany, Troy and other places 
in which much typhoid fever existed. Yet a study of the 
vital statistics of New York City does not support the idea 
that much typhoid fever is conveyed by ice, because while 
ice is almost universally used in that city its death-rate from 
typhoid fever has always been and now is exceptionally 
low for an American city. Boston, on the other hand, 
while having (as New York also has) an excellent water 
supply, is supplied with ice of great purity ; and yet the 
death-rate from typhoid fever in Boston is considerably 
higher than in New York. Again, the cities of Lowell and 



ICE SUPPLY AND THE PUBLIC HEALTH 2$9 

Lawrence have long been supplied chiefly with ice cut from 
the polluted and infected Merrimac (cf. pp. 207-212). 
Formerly, owing to polluted water supplies, both suffered 
severely from typhoid fever, though not, as might have 
been expected if ice were the cause, in July and August 
when ice is most used, but generally much later. With 
the introduction of purer water, the ice supply remaining 
the same, typhoid fever in both cities has fallen to the level 
of typhoid fever in other cities in Massachusetts having ice 
supplies of unquestioned purity. 

It was from the consideration of facts like these that the 
author was led to undertake the investigation which is de- 
tailed in the paper by himself and Mr. Winslow, and to 
conclude that in actual everyday life ice as a vehicle of 
disease is probably less important than might be supposed 
if one had in view only the fact that pathogenic germs may 
live for a long time in ice. There appear to be fortunately, 
numerous "mitigating circumstances," numerous conditions, 
which serve to decrease the dangers of ice as a vehicle of 
disease. And if all the facts are known and kept in mind, 
the various contradictory phenomena, which at first seem 
hard to harmonize, may be satisfactorily explained. 

Briefly stated, the more important facts appear to be 
the following: (1) While it is true that some individual 
bacteria survive exposure to freezing and even very low 
temperatures, such conditions are highly unfavorable to 
bacteria in general, even of the same kind, especially if the 
exposure be prolonged. Water does certainly tend to purify 
itself, and under ordinary and favorable circumstances does 
actually and extensively purify itself, during freezing. On 
the other hand, such purification, while great, is usually 
incomplete. (2) Out of a number of individual bacteria of 
any kind subjected to freezing a large proportion usually 
perish, especially if they continue to be exposed to the low 
temperature for two or three weeks, but a small propor- 
tion survive. (3) There is good reason to believe that the 



260 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

efficiency of the survivors and their virulence is weakened 
both by their loss of numbers, and by freezing or by long 
exposure to low temperatures. 

These facts taken together with those already mentioned 
above enable us to explain all, or nearly all, the phenomena 
in question. They also enable us to draw important con- 
clusions concerning the dangers of the pollution of ice, and 
concerning ice supply and the public health. 

§ 6. — The Pollution of Ice 

Although from what has now been said it is clear that 
there is much truth in the popular opinion that water puri- 
fies itself in freezing, it is equally plain that too much reli- 
ance must not be placed upon this process. Ice should 
be made only from good raw materials, i.e. from waters 
which are pure and potable; and this is doubly true if 
" artificial " rather than " natural " ice is to be used for 
public or private supplies. The processes of harvesting 
natural ice, and of delivering it to the consumer, still leave 
much to be desired. The use of horses whose droppings 
fall on the ice during the "ploughing" or cutting of the ice 
fields ; the uncleanly habits of the workmen employed ; 
the floating of the blocks through less pure, or actually pol- 
luted water, on their way to the ice-house ; their storage, 
often in a packing of old and dirty hay or sawdust ; and 
their final delivery into family, club or hotel refrigerators 
by common workmen after only hasty brushing with some 
ancient cloth or broom, — these conditions illustrate the 
need of improvement. Fortunately, however, ice in sum- 
mer is usually bathed superficially in water from its own 
melting and thus roughly cleansed, so that grave danger 
from the sources mentioned is probably relatively rare. 

In warm countries artificial ice is much used, and as pro- 
cesses of manufacture improve, it is likely to be more and 
more used everywhere. The author is strongly of the opin- 









NATURAL VS. ARTIFICIAL ICE 261 

ion that, generally speaking, such ice is likely to be inferior to 
the best natural ice. It is liable to be made from impure 
water ; when so made it has far less chance to purify itself 
by freezing; and, worst of all, it is promptly consumed; so 
that storage and the destruction of any microbes, which it 
may contain, by exposure for a long time to unfavorable 
conditions are not likely to occur. It is worthy of note 
that precisely as old (or stored) water is preferable to new, 
so also is old (or stored) ice. (Cf. pp. 237, 249.) 

§ 7. — Recapitulation 

From what has now been said we may derive the fol- 
lowing inferences and conclusions : there appears to be 
good ground for the popular belief that natural ice con- 
siderably purifies itself in freezing. The ideal and most 
favorable condition is that offered by a lake of pure, quiet 
and deep water in a region remote from human habitation. 
In such a case, on a still, cold night, the surface of the lake 
chilled by the freezing air hardens into a thin and delicate 
mirror composed at first of shooting, interlacing crystals. 
Each of these, as it forms on the very surface of a mother- 
liquor which is itself almost wholly pure, readily pushes 
aside most foreign substances such as bacteria, though be- 
tween the shafts of neighboring crystals or on their surfaces 
a few may be caught and confined. A little later, the first 
horizontal skimming of ice having been formed by the inter- 
locking or other union of crystals, fresh crystals send shafts 
downward into the now more quiet water just beneath them, 
and, the cold continuing, join themselves firmly to the layer 
already formed. But now quiet reigns below the ice, 
and gravity incessantly drags downward through the water 
everything within its reach. The purest layer of water, 
therefore, is now the highest, and into this fresh crops of 
crystals are steadily growing from above. Thus it happens 
that the uppermost layer of the ice is least pure, for this 



262 ICE AS A VEHICLE OF INFECTIOUS DISEASE 

includes more of the dust of the air, more floating matters, 
and is formed without any overlying sheltering solid layer 
such as, after its formation, stills the water and shields 
the under layers. This ideal condition, however, is rarely 
found. An impure pond or river is too often the source 
of supply. A sudden freeze often follows a thaw which 
has made turbid and dirty the waters from which the ice 
is then derived ; or a snow falling during a dry and windy 
period collects from the air a vast amount of dirt and falls 
upon pure ice, finally thawing and then freezing, only to 
weld itself as poor and porous " snow ice " to the better, 
purer ice beneath it. 

Still, when all has been said that can be said against ice 
as a vehicle of disease, and while it cannot be denied that 
ice may at any time under suitable conditions readily serve 
as such a vehicle, it nevertheless remains true that water 
certainly strongly tends to purify itself in freezing, and 
that no considerable amount of disease has ever been satis- 
factorily traced to ice either as source or vehicle. As a 
vehicle of disease, ice is plainly far less dangerous to the 
public health than is either water or milk. 1 

1 For an interesting discussion of the subject of " Ice Supply and the Public 
Health," see Journal of 'the Massachusetts Association of Boards of Healthy XI. 
4 (December, 1901), pp. 123-143. Also, H. W. Hill, M.D., " An Investigation 
of the Boston Ice Supply," Boston Medical and Surgical Journal, November, 

21, I90I. 



CHAPTER XI 

ON MILK AS A VEHICLE OF INFECTIOUS DISEASE. THE POL- 
LUTION AND INFECTION OF MILK. MILK SUPPLY AND THE 
PUBLIC HEALTH 

§ I. — Milk as Food for Microbes and Mankind 

Among all the vehicles of infectious disease there is 
perhaps none more dangerous than milk. This fact is 
the more remarkable because milk has always been one 
of the most trusted of human foods. Clothed in a veil of 
white ; associated with the innocence of infancy ; of high 
repute for easy digestibility ; believed to represent in per- 
fection a natural dietary, popular and cheap, — milk has 
always deservedly held a high place in public esteem. Of 
late years, however, while maintaining its reputation in 
respect to cheapness, food value, blandness and digesti- 
bility, it has, in the eyes of physicians and sanitarians at 
least, come to be regarded, while in the uncooked condi- 
tion, with general suspicion. The principal reason for this 
change of opinion is to be found in the fact that numerous 
epidemics of infectious disease have been traced with more 
or less of certainty to milk supplies ; while the development 
of the modern science of bacteriology has tended to show 
that milk is a peculiarly favorable culture-medium for many 
species of bacteria, and may be therefore justly suspected 
of serving as a dangerous vehicle for the germs of infec- 
tious disease. It is doubtful, to say the least, whether any 
disease germs, under ordinary circumstances, ever really 
multiply in a fairly good drinking water, even when sew- 
age-polluted, owing to the lack of a favorable environment ; 

263 



264 MILK SUPPLY AND THE PUBLIC HEALTH 

but the very qualities which make milk a good food for man- 
kind tend to make it likewise a good food for microbes, and 
there is only too much reason to believe that under certain 
circumstances some disease germs may not only survive, but 
even multiply, in fresh, pure milk, especially if it be kept 
warm. 

§ 2. — Origin of the Modern Distrust of Uncooked Milk 

For the reasons given in the preceding paragraph, there 
is to-day among physicians and sanitarians a widespread 
distrust of uncooked milk, and it must be admitted that the 
more the subject of milk supply in relation to the public 
health is investigated, the more cause there appears to be 
for uneasiness. Moreover, the conditions under which cows 
are kept, and the opportunities which exist for the pollution 
of milk, tend to confirm rather than remove this distrust. 
Aside from the fact, which would be regarded as highly 
peculiar if it were not so familiar, that milk is drawn 
directly from the body of an animal and therefore occu- 
pies an unique position among all human foods except 
that of infants, there remains the obvious circumstance 
that the milk supply constitutes one of the oldest indus- 
tries known to man. There is every reason also to believe 
that it is not only old, but old-fashioned. 

It is of recent years only that milk supply has come to 
be regarded as of importance to the public health. Pre- 
vious to 1 88 1 it was not generally known that milk is one 
of the readiest vehicles of infectious disease. It is said 
that the first epidemic of typhoid fever traced to milk was 
one in 1857, studied by Dr. Michael Taylor. In 1867 the 
same epidemiologist showed that scarlet fever might be 
distributed in a similar way, and simultaneously Professor 
Oswald Bell arrived at the same conclusion through his 
investigation of an outbreak of that disease. In 1877 an 
epidemic of diphtheria was traced to a milk supply. These 
and other cases which had been reported were brought 



MILK AS A VEHICLE OF LNFECTIOUS DISEASE 265 

together in 1881 by Mr. Ernest Hart, and laid before the 
International Medical Congress of that year in a striking 
paper, which at once drew universal attention to milk 
supply as a vehicle of infectious disease. Mr. Hart in his 
paper gave the history of fifty epidemics of typhoid fever, 
which up to that time had been charged to infected milk, 
besides fifteen epidemics of scarlet fever, and four of diph- 
theria. "The record," says the eminent medical writer 
from whom these statements are taken, " since 1881 has 
not been less striking ; indeed, since the method of inves- 
tigating these occurrences has been more generally under- 
stood, milk has been constantly and justly incriminated as 
a cause of zymotic disease in man." 

§ 3. — The Fermentations of Milk 

If the year 1881 was important to the milk-supply indus- 
try and the public health for the reasons just mentioned, 
it was no less so for another and very different reason. It 
will be remembered that it was in this year that Koch's 
method of solid cultures for bacteria was introduced 
(see p. 53), and this method soon made it easy to investi- 
gate with some accuracy the ordinary fermentations of milk 
by observing the numerical increase of its bacterial fer- 
ments and their variety, while also studying their progres- 
sive effects upon the milk itself. The same method, which 
in other fields led to the discovery and elaborate study of 
the special ferments or germs of certain infectious diseases, 
such as typhoid fever, Asiatic cholera and diphtheria, made 
possible also the study of the behavior of these germs in 
milk, with the result that evidence was quickly obtained 
proving that under certain circumstances, milk offered to 
them an admirable culture-medium. 

Further investigations along these lines have shown that 
city milk is often in an advanced stage of decomposition, 
and therefore far removed from the normal milk which is 






266 MILK SUPPLY AND THE PUBLIC HEALTH 

drawn by the infant from the mammary gland of the 
mother. It has long been known that bottle-fed babies in 
cities show a much heavier mortality than those fed nor- 
mally ; and investigations appear to have proved that this 
is due, in part at least, to the unsatisfactory condition of 
city milk supplies. It is now well known that city milk is 
not only often falsified, but also frequently filthy, stale and 
half fermented. Moreover, the facts that tuberculosis is 
the cause of death of a larger number of persons than die 
of any other disease, and that tuberculosis is known to be 
common in cows, have naturally led many to suppose that 
numerous cases of this disease are due to the consumption 
of milk. More recently, also, it has been alleged on good 
authority that the mixed milk of a number of cows is 
seldom free from pus. 

§ 4. — Normal versus Fermented Milk 

By "normal" milk is meant milk as it flows from the 
teat of a healthy and well-fed mammal. Such milk is, as 
a rule, free from putrefactive bacteria. (Cf. § 7.) 

Almost immediately, however, normal milk is invaded by 
a host of such bacteria, which find their way into it from the 
air, the dust of the stable, the cheesy remains of previous 
milkings in the angles of the pails and other appliances, 
the hide of the cow, or the hat or hands of the milker. 
It is held, also, that normal milk may be seeded with bac- 
teria even before leaving the teat, the so-called " foremilk " 
having been found by numerous observers to contain a con- 
siderable number of bacteria, which are supposed to have 
come from infection, from without, of the milk in the main 
duct of the teat. However this may be, there is no ques- 
tion that normal milk is relatively free from bacteria, and 
fresh or unfermented. 

It is worth while to observe, in passing, that normal milk, 
under natural conditions, arrives in the stomach of the 



IMPORTANCE OF SANITARY MILK SUPPLIES 267 

suckling almost instantly after leaving the teat ; for, as we 
shall show, milk as obtained in cities and from public sup- 
plies in general is very different in this respect. City milk 
is always more or less old and fermented, more or less stale 
and more or less dirty. Between the time of its leaving the 
teat and its arrival in the stomach of the bottle-fed city 
infant, cow's milk has too often travelled over a long dis- 
tance ; too often undergone damaging exposure to dirt and 
air; and too often suffered extensive fermentation or decom- 
position. It is impossible to avoid the conclusion that it is, 
for these reasons, comparatively abnormal. 

§ 5. — Infantile Diarrhoea and Cholera Infantum 

Various observers have attributed to unsound milk, not 
only the high death-rate of bottle-fed infants in cities, 
but also certain special diseases, such as the infantile 
diarrhoea of summer and cholera infantum. There is rea- 
son to believe that in many instances, at least, unsound 
milk has much to do with these disorders, and in support 
of this view it is urged that the substitution of cooked 
(Pasteurized or sterilized) milk, for uncooked or raw milk 
swarming with bacteria, does away in a large measure with 
the troubles referred to. It is perhaps still too early to 
speak with accuracy on this subject, but the tendency cer- 
tainly is, among those who have looked into the matter, to 
consider unsound milk as the source of many of the most 
serious troubles of infancy. Experiments conducted in 
hospitals and nurseries seem amply to justify this conclu- 
sion, and the supreme importance of a sanitary milk supply 
for such establishments is now generally conceded. 

§ 6. — The Pollution of Ordinary Milk 

Bacteriologic and microscopic examinations reveal the 
fact that ordinary city milk is highly polluted. Numerous 
observers all over the world have reported the presence in 



268 MILK SUPPLY AND THE PUBLIC HEALTH 

ordinary city milk of vast numbers of bacteria ; and inquiry 
as to the source of these micro-organisms has led to the dis- 
covery that milk is too often polluted, to a serious degree, 
by the dust of the air, the dung of the stable, and the un- 
cieanness of pails, cans and other milking utensils, such 
pollution being unfortunately hidden by the opacity of 
milk, and unsuspected because of the idea of purity usually 
associated with its color. The fact appears to be that the 
dairy industry is, as a rule, still in a very primitive condition. 
The following realistic statement, made in the author's 
hearing by a member of a suburban Board of Health, 
describes a condition which was only too common in rural 
New England in the last quarter of the nineteenth century, 
and has not yet wholly disappeared. 

" If we consider merely the matter of cleanliness and the prevention 
of filth in milking the cows and taking the product to market, we still 
have a very large and difficult question to deal with. No doubt Boards 
of Health can do something to improve cow stables, to secure better 
ventilation, and more cleanliness — they can do something ; but from 
what I have seen myself (and I was brought up on a farm), I know 
that a large part of the filth which gets into the milk gets there in ways 
beyond the direct control of Boards of Health, for it gets there by the 
careless behavior of the milker. 

" The day has gone by when a pretty milkmaid went, in clean, white 
apron and with shining milk pail, to milk the cow with the crumpled 
horn out among the buttercups of a dewy morning. Instead, some old 
fellow stumbles out of the house and to the barn, with the stump of a 
clay pipe in his mouth, and wearing overalls and boots saturated and 
covered with the filth acquired by a winter's use. When he reaches 
the barn he selects some recumbent cow, kicks her until she stands up, 
dripping and slimy, and as he is a little late and the milk will have 
hardly time to cool before the man who carries it to the city will come 
along, he does not stop to clean up behind the cow, but sitting down 
on a stool, proceeds to gather the milk and whatever else may fall into 
a pail which perhaps is clean and perhaps is not. Of such refinements 
as washing the udder of the cow or wiping her flanks, he has never 
heard. If he has, it is only to scoff. Then he strains the milk behind 
the cows. That is bad enough, but it is not all the story. Every one 
knows that in straining the milk the strainer becomes obstructed more 



THE POLLUTION OF MILK 269 

or less with dirt and filth, and when the milk does not run fast enough, 
he would be a rare milker who hesitated to scrape away a place with his 
fingers so that the milk might run more freely. Those who have seen 
certain fingers, as I have, know what that means." — E. Irving Smith. 
Journal Massachusetts Association of Boards of Health, II, 2, p. 33 
(1892), 

§ 7. — Systems of Public Milk Supply. (A) Normal Milk 

Supplies 

The primitive, original and fundamental form of milk 
supply is that in which the mammal — cow, camel, elephant, 
goat, sheep, mare or man — suckles its young. In this case, 
the milk supplied by the parent passes almost instantane- 
ously from the milk gland into the stomach of the young 

— without lapse of time, without exposure to air or vessels, 
without human handling, manipulation or falsification — 
precisely as nature has prepared it. The only possibility 
of fault to be found with it, from the sanitary standpoint, 
is the opportunity of damage from the parent, in case that 
parent is unhealthy or ill fed. If the parent is healthy 
and well fed, such milk deserves the name of normal milk. 
Normal cow's milk, then, may be defined as milk as it 
flows from the udder of a healthy and well-cared-for cow. 

§ 8. — (B) Country, or Domestic, Milk Supplies 

Next in complexity comes the private, or domestic, 
supply, in which a family obtains its milk from its own 
cow or cows. This is the system which prevails on ordi- 
nary farms and in small villages, and survives sometimes 
as a luxury of the wealthy, even in large cities. In this 
case the milk is no longer strictly normal. Between the 
producer (the cow) and the consumer (the individual who 
swallows the milk) have come in one or more middlemen, 

— the milker, the housewife, the housemaid, as may be. 
Moreover, the milk has been more or less exposed to air, 

— possibly dust-laden, and always carrying microscopic 



270 MILK SUPPLY AND THE PUBLIC HEALTH 

germs of fermentation; to vessels, — pails, pans, strainers, 
— often richly seeded with similar microscopic organisms ; 
and time has elapsed, longer or shorter, so that these 
organisms have caused the milk to "work" or ferment, 
slightly or extensively as the case may be. This in itself 
marks a departure, often trifling but always real, from the 
absolutely normal milk supply, such as calves and infants 
naturally enjoy. The sources of danger are here much 
increased, for it is no longer merely the question of 
having a healthy, well-fed parent; we have now also 
to consider a possible contamination by the milker, the 
housewife, or other " middleman," before the milk enters 
the stomach of the consumer, and also those natural altera- 
tions which milk undergoes after being seeded with the 
germs of fermentation, during the time which elapses 
between its exit from the teat of the cow and its entrance 
into the stomach. In well-regulated families, however, 
the risk of damage so resulting is, from a sanitary point 
of view, comparatively slight ; and those are fortunate who 
may enjoy the privilege of possessing a milk supply of this 
simple, primitive kind. 

Not by any means the least important fact in this 
domestic system of supply is the possibility of complete, 
personal acquaintance on the part of the consumer with 
the sources of his supply, and a consequent more or less 
extensive control over them. This, as we shall see, he 
almost unconditionally surrenders when he becomes an 
ordinary dweller in a great city. 

§ 9. — (C) Village or Suburban Milk Supplies 

As man comes to live in larger villages and towns, some 
families give up the keeping of cows and buy milk of their 
neighbors, who, in order to supply them, keep more cows. 
The personal acquaintance of the consumer with the exact 
sources of his supply diminishes, and his personal control 



VARIOUS SYSTEMS OF MILK SUPPLY 2/1 

is somewhat relaxed, though he still keeps up a general 
knowledge and supervision, and may, if he chooses, know 
and do more about his milk supply at any time. But, as 
the neighbor who supplies him keeps more cows, and more 
men, and uses more cans, and needs more time to distribute 
his milk, each possible source of damage to the milk becomes 
more important and the departure from the normal is, neces- 
sarily, gradually and constantly greater. 

§ 10. — (D) City (Railroad) Milk Supplies 

Finally, as the city continues to grow larger, the milk 
farms are pushed farther and farther away, until a state 
of things is reached in which the farmer can no longer 
himself deliver milk to the consumer, even with the aid of 
fleetest horses. The railroad is called in, the contractor, 
or some similar middleman, appears, and the farmer now 
becomes merely the producer. But the consumer cannot 
send to the railroad for his milk, and so another carrier, 
with special wagons adapted to the purpose, passes to and 
fro between the railroad and the consumer. This person 
is known to the consumer as " his milkman " ; but, as a 
rule, he is a very different kind of person from the farmer, 
the original type of "milkman." In this final form of milk 
supply the producer may have no idea whatever of the 
final destination of his milk; and the consumer, as a rule, 
neither knows nor cares where the milk which he buys 
comes from. The personal relation between consumer 
and producer is totally lost, and the middleman comes to 
hold the position of principal importance, as the only per- 
son in touch with all. These circumstances, and the very 
size of the system, tend to make it largely mechanical, and 
all connected with it merely subordinate parts in a great 
machine which, for good or ill, must work on incessantly. 

With the rapid growth of cities and the development of 
railroad facilities, it is likely that something like the sys- 



272 MILK SUPPLY AND THE PUBLIC HEALTH 

tern last described, and which now holds good only for the 
largest cities, will come to exist, to a greater or less extent, 
even in smaller communities, and it is well that these ten- 
dencies, which concern farmers, middlemen and consumers 
alike, should be carefully noted by the sanitarian. 

Under this system the milk is often two days old, and 
therefore relatively stale and half fermented, before it is 
actually consumed. It also necessarily passes through 
many hands en route, and is therefore accessible to manipu- 
lation, adulteration and contamination. 

§ n. — Milk Supply in Hot Countries 

In tropical countries the systems of public supply just 
described do not usually prevail, doubtless owing to the 
fact that ice is not ordinarily available, and even if it were, 
might be inadequate for the satisfactory preservation of 
the milk. 

It is said that among the Arabs milk is either consumed 
absolutely fresh when drawn from the cow, or else is 
allowed to sour before it is used. In Naples, and many 
other cities in warm climates, cows or goats are driven 
through the streets, and milked by their owners before the 
doors, and in the presence of, the consumers. The herds 
of goats thus driven slowly through the streets of conti- 
nental cities, led by a goat-herd playing on some simple 
musical instrument, are familiar sights to travellers. It is 
stated that the Chinese never drink either water or milk 
without first having boiled it. 

In all these and other customs of mankind regarding 
milk supplies, the sanitarian can readily trace the results 
of human experience. Absolutely fresh milk, approaching 
as it does the normal condition, is almost everywhere a 
favorite food. If, however, owing to local conditions, such 
as density of population, climate or the nomadic habit, 
milk cannot be obtained absolutely fresh, it is, and should 



MILK AS A VEHICLE OF TYPHOID FEVER 273 

be, either cooked or soured before it is used. By cookery, 
the germs of decomposition and infection are destroyed ; 
by souring, acid is produced, which is similarly unfavorable 
to many germs of decomposition and infectious disease. 

§ 12. — Epidemics of Typhoid Fever in Massachusetts 
traced to Infected Milk Supplies 

Several extensive epidemics of typhoid fever in Mas- 
sachusetts have been traced to infected milk supplies, 
and the same thing is true, generally speaking, all over 
the world. As the author is naturally most familiar with 
those epidemics which he has himself investigated, he 
has chosen for illustration examples drawn from his own 
experience. 

§ 13. — The Springfield Epidemic' 1 

In August, 1892, the State Board of Health of Massa- 
chusetts was informed by the local Board of Health of 
Springfield that an epidemic of typhoid fever had appeared 
in that city. Investigation showed that the cases were not, 
as might have been expected, among the poorer classes of 
the people, nor in the midst of unsanitary surroundings, but 
in a district well provided with sewers, by no means over- 
crowded, inhabited by a superior class of citizens dwelling 
for the most part in separate and detached houses of high 
grade, each house surrounded by a lawn or grass plot, and 
standing somewhat back from the street. The plumbing 
arrangements were unusually satisfactory, because the 
houses were new and their owners well-to-do. 

Various theories prevailed among the people to account 
for the epidemic, but all of these were easily disproved 
except that which attributed the cause to an infected milk 

1 For the full report, illustrated by diagrams, see Twenty-fourth Annual 
Report State Board of Health of Massachusetts (for 1892), p. 715. Boston, 
1893. 

T 



274 MILK SUPPLY AND THE PUBLIC HEALTH 

supply. Almost every one of the persons affected with 
the disease was shown to have swallowed milk supplied 
by a particular milkman, and patient inquiry eventually 
revealed the fact that the milk distributed by the milkman 
in question was derived from a farm, several miles from 
the city, upon which there had lately been a case of 
typhoid fever. The excreta of the patient had not, at least 
for a time, been satisfactorily disinfected, and in one or 
more of several ways had probably found access to the 
milk produced on the farm and sent to Springfield. 

§ 14. — The Somerville Epidemic 1 

In the same year (1892) a small epidemic of typhoid 
fever appeared in a particular section of Somerville, Mass. 
Inquiry soon showed that all of the cases were supplied 
with milk by one milkman. This time no typhoid fever 
was discovered on the farms from which the milk was de- 
rived, but it was finally disclosed that a son of the milk- 
man, whose duty it was to transfer the milk from the 
larger cans, in which it came from the farms by railroad 
to the city, to the little cans in which it was furnished to 
the consumers, and who in various ways came more or less 
in contact with the milk, had been himself, a little earlier, 
a sufferer from, and was finally a victim of, typhoid fever, 
and the probable source of the disease among his customers. 

§ 15. — The Cambridge Epidemic 

In August, 1896, a considerable epidemic of typhoid 
fever appeared in the city of Cambridge, Mass., and it 
soon became evident that it was due to infected milk. 
Subsequent investigation revealed the fact that here also, 
as in the Somerville case, no typhoid fever existed on the 
farms from which the milk was derived ; but that among 

1 Op. cit., footnote, p. 273. 



MILK AS A VEHICLE OF TYPHOID FEVER 275 

the workmen who manipulated the milk in the milk-house 
of the local (Cambridge) dealer there existed two, and 
possibly three, mild, and at first unrecognized, cases of 
typhoid fever. 

§ 16. — Epidemics traced to Skimmed {Separated) Milk, 
and Creameries 

In August and September, 1894, a small epidemic of 
typhoid fever appeared in the city of Marlborough, Mass. 
Various "theories" of the cause of the outbreak were 
held or suggested, and the local newspapers contained 
numerous letters on the subject, some alleging that the 
water supply was infected, some that the sewers were to 
blame, and some that accumulations of filth, especially 
dump-heaps, were responsible. The localization of the 
cases, however, not only disproved these " theories," but 
also suggested milk as the probable cause. 

It soon became evident, nevertheless, that none of the 
regular milkmen were involved, the cases apparently 
deriving their milk supplies from a variety of different 
sources. Eventually, however, it turned out that there 
existed within the city itself a creamery from which was 
despatched daily a wagon loaded with skimmed milk ("sepa- 
rator " milk), and that nearly all the cases of typhoid fever 
had been supplied with such skimmed milk either from this 
wagon or directly from the creamery itself. Further inves- 
tigation showed that the driver of the skimmed-milk wagon 
was at the time of the inquiry living on the upper floor of 
the creamery, and just recovering from a severe attack 
of typhoid fever. This young man had not only been 
the driver of the wagon, but had also worked over the 
milk, transferring it, filling the cans, and otherwise making 
himself useful about the creamery. In the investigation 
of this case, which was made by the author on behalf of 
the State Board of Health of Massachusetts, aid was de- 



276 MILK SUPPLY AND THE PUBLIC HEALTH 

rived from the report of Dr. Welply, then recently pub- 
lished, on an epidemic of typhoid fever traced by him to a 
creamery in Ireland, and disseminated by separator milk. 1 
In this case milk from a farm belonging to a family suf- 
fering from typhoid fever was taken to a creamery, and 
appears there to have infected the whole mass of separated 
or skimmed milk, through which it was distributed to 
numerous other families. 2 In the reprint of Dr. Welply's 
papers " four other epidemics due to separated milk " are 
referred to. 

§ 17. — The Question of Tuberculosis in Milk 

Inasmuch as milk is one of the most universally trusted 
and widely employed of foods, while cows are known to 
suffer seriously from tuberculosis and this disease sur- 
passes all other diseases as an agent of death in the 
human family, milk has naturally fallen under the gravest 
suspicion as a vehicle of tuberculosis. Satisfactory proof 
of any such complicity as is suspected is, however, exceed- 
ingly difficult to obtain. Owing to the fact that tuber- 
culosis is commonly a disease of slow development, it is 
almost impossible to trace any particular case in the human 
family to any particular infection, and the very abundance 
of opportunities for infection makes it hard to prove that 
one, and only one, source existed. It is hard to resist the 
belief that if a cow is suffering from tuberculosis of the 
udder, her milk is tolerably certain to be infected. Nor is 
it necessary even to assume the presence of udder tuber- 
culosis in order to admit the possible infection of milk. 
Cows affected with pulmonary tuberculosis may, and often 

1 Dr. J. J. Welply, " Creameries and Infectious Disease," The Lancet, 
April 21, 1894. See also, by the same author, " Creameries and Infectious 
Diseases," London, Balliere, Tindall and Cox, 1895. 

2 For a full account of the Marlborough epidemic, see report by the author 
in Twenty-sixth Annual Report State Board of Health of Massachusetts (for 
1894), p. 765. 



MILK AS A VEHICLE OF TUBERCULOSIS 27.7 

do, lick their own flanks or udders and those of other cows, 
and conceivably may readily leave there fresh germs of 
tuberculosis from their sputum, which germs, barely dried, 
may soon after fall, or be brushed during milking, into the 
milk pail. 

As a matter of fact, germs apparently identical with those 
of tuberculosis have been detected by microscopical exami- 
nation in the milk of cows in which no udder disease could 
be discovered by physical signs, and these may have got 
in in the way suggested. We may remark, in passing, that 
such examinations are not competent to determine whether 
the germs in question are alive or not. This point can 
only be determined by cultivations, or, better, by inocula- 
tion experiments. 

The most instructive and valuable evidence that we 
have comes from inoculation experiments, in which a num- 
ber of healthy susceptible animals (guinea-pigs are gen- 
erally used) are selected, and divided at random into two 
groups. One group is kept, as a control, under conditions 
precisely similar to those of the other, except that its 
members are not inoculated. To the members of the 
other group are given subcutaneous injections of milk 
suspected to contain the bacilli of tuberculosis. In cer- 
tain experiments of this kind the inoculated animals have 
actually perished after a time with tuberculosis, while the 
corresponding control animals have kept free from it. 
Such experiments certainly seem to prove beyond all 
question that milk may be a vehicle of tuberculosis. They 
do not, however, prove that bovine tuberculosis is as readily, 
if it be at all, communicable to human beings by milk; and 
we have experimental evidence that human tuberculosis is 
not readily, if ever, conveyed to cattle. The whole sub- 
ject, in brief, requires further elucidation. 

Reports of cases in which a family used the milk of 
a tuberculous cow and afterward suffered severely from 
tuberculosis, should be received with caution. They are 






278 MILK SUPPLY AND THE PUBLIC HEALTH 

almost always open to the suspicion and the possibility of 
being examples of coincidence, rather than cause. 

§ 18. — Scarlet Fever and Diphtheria in Milk 

A number of epidemics of scarlet fever and diphtheria 
have been attributed to milk as a vehicle, but the number 
is small in comparison with those of typhoid fever traced 
to milk. Moreover, a careful review of the evidence in 
these cases is calculated to leave the student somewhat 
less well satisfied that milk was really in some of the in- 
stances the sole vehicle of the disease. 

§ 19. — The Protection of Milk Supplies from Pollution 

The milk-supply industry, as has been said above, is still 
to a great extent in a primitive condition. The ordinary 
dairy farmer, no matter how honest or well-meaning, often 
has not the smallest conception of the sanitary aspects of 
his art. It is exceedingly unfortunate that dirt in milk 
cannot readily be observed, and that the characteristic odor 
of milk masks to a great extent evidences of decomposition 
which might otherwise be plain. What is needed is a cam- 
paign of education among the farmers who produce milk, 
concerning, first, the simple protection of a readily putres- 
cible fluid from pollution with dirt and other elements of 
decay ; and, second, the sanitary protection of milk from 
infection. It is no doubt a difficult matter to make sure that 
the hands and the clothing of the milkers of cows shall be 
thoroughly clean ; that the udder and teats shall be washed, 
or at least wiped thoroughly with a damp cloth, before the 
milking begins ; that the tail of the cow shall not make even 
occasional excursions through the pail during the milking ; 
that cows shall be, like horses, groomed and kept clean so 
that caked dung shall not cling to their flanks, to drop, with 
dandruff from their hides, into the pail ; that pails and cans 
and strainers shall be sterilized with steam or scalding 



THE INFECTION OF MILK 279 

water so thoroughly that yellowish cheesy matter alive 
with myriads of bacteria shall not fill their corners or 
cracks ; but it is these simple items, indispensable to 
cleanness, which, carefully attended to, will not only 
improve the milk, from a sanitary point of view, but also 
prolong its " life " or keeping qualities, and thereby in 
the end richly reward the producer who is willing to 
"take pains." (Cf note on p. 392.) 

It should never be forgotten that if drinking water 
were to be drawn, as milk is, from the body of a cow 
standing in a stable, by the hands of workmen of ques- 
tionable cleanness, and then stored and transported over 
long distances in imperfectly cleaned, closed cans ; being 
further manipulated more or less, and finally left at the 
door at an uncertain hour of the day, few would care 
to drink it, because its pollution and staleness would 
be obvious. It is clear, moreover, that milk requires, 
and deserves, even more careful treatment than water, for it 
is more valuable, more trusted and more readily falsified or 
decomposed. Nevertheless, until very lately, milk while 
legally protected from dilution by water has received little 
or no attention from boards of health on the simple ques- 
tion of pollution. It is cheering to observe, therefore, that 
steps are at last being taken even in this direction. 

§ 20. — The Protection of Public Milk Supplies from 
Infection 

It will be convenient and natural to divide this subject 
into two ; namely, (a) protection from infection by man, and 
(b) protection from infection by the cow. 

(a) The occurrence of numerous epidemics, in which it 
appeared that some person or persons working over the 
milk had infected it, has led to rules and regulations — 
often having the force of laws — governing the conduct of 
dairies by persons known to be diseased, or otherwise aim- 



280 MILK SUPPLY AND THE PUBLIC HEALTH 

ing to protect the public health. To a brief consideration 
of these we shall come in the next section. Here we shall 
simply seek to develop the principles which should under- 
lie such rules and regulations by considering in detail how, 
precisely, cows' milk may become infected from sources 
other than the cow, and especially through human beings. 

Milk may become infected almost as soon as it is drawn 
from the cow by germs derived from the hands of the 
milker or from his clothing. If, for example, a milkman 
or milkmaid happens to be in the early stages of some 
infectious disease such as typhoid fever, cholera, scarlet 
fever, or diphtheria, and is not personally very cleanly, 
fresh infectious materials (faecal, epidermal or mucous) 
may easily obtain access to hands or fingers, and in the 
process of milking be readily communicated to the milk. 
It is unfortunately a not unknown practice among milkers, 
in America at least, in order to soften and clean the some- 
times dry and dusty teats of the cow, to begin by milking 
first with one hand and then with the other into the palm 
of the free hand held as a cup, and with the milk so drawn 
to bathe and soften the several teats before formally begin- 
ning to milk into the milk pail. In this case the hands often 
still drip milk for a moment or two directly into the pail, and 
the opportunity to transfer infectious matters from the hands 
of the milker into the warm, fresh milk, which is a good 
culture medium for many bacteria, is manifest. Clearly, no 
person affected with transmissible disease should be allowed 
to act as a milker, for even when no such moistening of 
the teats with milk as has been described occurs, the mere 
pressure of hands upon teats, which is a necessary part of 
the process of milking, may suffice to detach portions of 
infectious material, possibly merely microscopic in size, and 
cause them to fall into the milk pail. 

In practice, however, this problem is a very difficult one, 
because it is often nearly or quite impossible to detect the 
presence of an infectious disease in its earliest stages. In 



THE INFECTION OF MILK BY MILKMEN 28 1 

typhoid fever, for example, it may be a week or even a 
fortnight before the disease declares itself in an unmistak- 
able manner ; and it is admitted that persons very fre- 
quently have this disease not only in a form so mild that 
some never take to their beds (ambulatory or " walking" 
cases), but that they never even suspect that they have so 
serious a disease. It is plain, therefore, that legislation, 
even when honestly and faithfully obeyed, is not enough. 
Too often its application would resemble the locking of the 
stable door after the horse had been stolen. There is, 
indeed, only one absolute safeguard against the dangers of 
infection from diseased milkmen, and that is the most abso- 
lute and scrupulous cleanness, not only personal but, so to 
speak, professional also. The milkers should be thoroughly 
clean, and the operation of milking should be conducted 
almost as a surgical operation is, namely, with extreme 
cleanliness and constant dread of disaster from infection. 

What has been said of the possibilities of infection of 
milk by the milker is no less true of all manipulation or 
" handling " of milk. If at any time milk is exposed to 
infectious matters from the hands of persons working over 
it, or to infected dust or epidermal scales from the cloth- 
ing of such persons, danger exists. Several epidemics of 
typhoid fever have been traced by the author to persons 
manipulating or handling milk between the producer and 
the consumer. Those who desire to do so may pursue this 
subject in detail in the published reports of these cases. 1 
It is probable that diphtheria and scarlet fever are more 
or less readily conveyed in the same way. If the infectious 
materials of the latter disease, as seems likely, can be 
conveyed in the epidermal scales during the " peeling " 
(desquamation) period, it is easy to realize how readily they 
may find access to milk either from the skin of the patient 
or the clothing of a friend of the patient. As regards 

1 See references above to Springfield, Somerville, and Marlborough epi- 
demics. 



282 MILK SUPPLY AND THE PUBLIC HEALTH 

diphtheria, the wonder is not that it appears to be some- 
times conveyed by milk, but that more cases have not been 
traced to this source. 

One of the most objectionable practices on the part 
of milk dealers in Boston is the custom, which is rarely 
if ever departed from, of tasting every large can of milk 
on its arrival in the city This is done to detect sour milk 
and enable the buyer (or middleman) to protect himself 
against the purchase of stale or ill-flavored milk. The 
"tasting" consists in removing the plug, applying the 
lips to the can, and taking into the mouth, as if for drink- 
ing, a small quantity of milk which is usually not swallowed 
but spat out again, generally upon the floor near by. Aside 
from the aesthetic considerations involved, it is apparent 
that the application to a mass of milk of lips perhaps asso- 
ciated with a throat charged with the germs of diphtheria 
is a most unsanitary procedure, and one that ought to be 
strictly forbidden. It is the appreciation of facts like the 
foregoing that has led to the establishment here and there 
of model dairies in which all possible precautions are taken 
to secure cleanliness and security against disease among 
both the workmen and cows composing the herd. To a 
brief account of these we shall presently return. 

{b) We may now briefly consider the principles which 
should govern sanitary endeavor to secure protection of 
the public health against milk infected by the cow herself. 
It is obvious that, inasmuch as milk is for the most part 
consumed uncooked and comparatively fresh, the opportun- 
ity for direct transfer of infection from cow to consumer 
is easy, and therefore that, generally speaking, diseased 
cows should not be used as sources of milk supply, On 
the other hand, it does not follow that a cow having a some- 
what diseased liver, kidney, or eye, may not give normal 
milk ; and in practice it is by no means easy, at times, to 
decide whether a cow is diseased at all, or, if so, to what 
extent ; or, finally, whether being herself probably some- 



INFECTION OF MILK BY DISEASED COWS 28.3 

what diseased, either temporarily or permanently, her milk 
is now, or is likely to be, affected. The matter is further 
complicated by the fact that the cow is a piece of property 
having a value to her owner, who naturally objects to her 
destruction or disqualification, and accordingly gives their 
fullest possible value to all doubts which exist as to the 
damage she may do. Moreover, veterinary medical science 
is not so advanced as to be in all cases thoroughly trust- 
worthy in diagnosis, so that the whole subject is in a very 
unsatisfactory condition. 

All parties interested agree that cows showing plainly 
and obviously the physical signs of advanced disease, of 
any serious sort whatever, should not be used for milk 
supply. It is only the diseases most difficult to diag- 
nose with certainty, and especially tuberculosis, about 
which there is much serious contention. Even in this 
case, where the physical signs are pronounced and appar- 
ently unmistakable, there is as a rule no serious difficulty 
in securing the exclusion of the affected animals from 
the herd of milch cows. It is chiefly concerning the more 
obscure and early cases that grave controversy arises, 
and this has reached an acute stage only since the dis- 
covery of tuberculin by Koch, and its recommendation by 
him (and more recently by others) as an almost infallible 
diagnostic agent for the detection of tuberculosis, followed 
by legislative enactments looking to the destruction of 
cattle and cows condemned by the results of tuberculin 
tests. Tuberculin appears to be a valuable reagent for the 
detection of this disease, but it is urged with some force 
that it is not infallible; that it is so delicate as to detect 
sometimes trifling lesions, perhaps in places where they 
would be very unlikely to do harm or so limited as to be 
readily recovered from or checked ; and that it damages 
normal, healthy cows by subjecting their tissues to a 
violent poison, if only for a time. For these and other 
reasons the owners of cattle in Massachusetts organized 



284 MILK SUPPLY AND THE PUBLIC HEALTH 

and secured the repeal of a statute involving a compulsory 
tuberculin test, and seriously interfered with the work of the 
State Cattle Commission. This is perhaps not surprising 
when we reflect that proof of the complicity of milk in the 
causation of tuberculosis is not very clear (see p. 277); 
and that it is not certain that tuberculosis of inner organs, 
such as may cause reaction under tuberculin, and yet is 
not revealed by physical signs, can affect the milk unfavor- 
ably. Further experience with tuberculin may serve to 
show whether the original legislation or its hasty repeal 
was in this case the wiser. 

It is not known or generally believed that typhoid fever 
can be communicated by the cow herself, either as a victim 
of that disease or as having drunk water infected with its 
germs. It is a question often asked during an epidemic of 
typhoid fever charged to milk, Can a cow that has drunk 
sewage-polluted water transmit the germs through her 
milk ? The answer is that, so far as is known, she cannot 
and does not. 

One of the most startling discoveries recently made in 
regard to infectious materials in milk is that of Dr. Stokes 
and an associate, of Baltimore, who investigated a curious 
creamy yellowish layer, of a slightly suspicious appear- 
ance, upon milk derived from a dairy tributary to that 
city. They found that the yellow layer was largely com- 
posed of pus, and finally traced its origin to a herd affected 
with garget. They even believed that they were able to 
trace the origin of the epidemic (which affected about 
eighty cows) to a milkman, who had probably brought in 
the germs from another state and by his hands conveyed 
the culture from cow to cow. The authors were led to in- 
vestigate examples of mixed milk from other herds, and 
finally reached the important conclusion that the mixed milk 
from almost any herd usually contains more or less pus. 

Scarlet fever possibly arising from cows suffering with 
that disease has already been dealt with (pp. 264, 278). 



THE DANGER OF USING RAW MILK 285 

The conclusion of the whole matter is sufficiently obvi- 
ous. The consumption of raw milk is always attended 
with grave dangers, partly from its usual pollution with 
dirt and dung, and the objectionable fermentations thus 
provoked, but chiefly from the fact that milk supply is 
an industry still in a primitive state, and that uncooked 
milk is liable to contain the germs of various infectious 
diseases derived either from the cow or from those persons 
who " handle " the milk. 

The remedies lie along the path of progress. Very 
much as modern sanitary or aseptic surgery differs from 
that which prevailed before the time of Pasteur and Lister, 
so the sanitary or aseptic milk-supply industry of the future 
will differ from that of to-day ; and precisely as successful 
sanitary surgery depends in the last analysis upon abso- 
lute cleanness, so also does the solution of the problem of 
successful sanitary milk supply. 

§21. — Safeguards against Polluted and Infected Milk 

As long as milk is consumed raw or uncooked, there will 
always be danger in its use. There is no possible way in 
which the absolute purity of raw milk can ever be proved 
or even established. The most that can be done with raw 
milk is to reduce the dangers of pollution and infection to 
their lowest terms ; but after all possible precautions have 
been taken in regard to the health of the cow and in re- 
gard to cleanness in the utensils employed and on the part 
of those who " handle " the milk, mistakes may be made 
or accidents may happen by which the milk shall be pol- 
luted or infected. It may be best in certain cases to take 
the risks involved and to use raw milk for infants or inva- 
lids. There is some important evidence pointing in this 
direction ; but after making every allowance for such cases, 
it still remains true that, from the standpoint of sanitary 
science, raw, uncooked milk is an unsafe food, and that 



286 MILK SUPPLY AND THE PUBLIC HEALTH 

whenever it is possible it should, before it is swallowed, 
be cooked or otherwise treated so as to destroy any disease 
germs it may contain. Various methods have been pro- 
posed or employed to this end, and to a brief consideration 
of the principles involved in these we may now pass. 

§ 22. — Sterilization 

This process has long had its prototype in domestic 
practice in the custom of " scalding " milk, and the experi- 
ence of generations has shown that repeated " scaldings " 
suffice to make milk " keep " a long time. Bacteriology has 
shown the reason why, which is simply that the ferments 
or bacteria which swarm in milk soon cause it to sour unless 
they can be killed, by heating or otherwise, or hindered 
in their activities by cold. The scalding process as con- 
ducted by the housewife has to be repeated in order to save 
the milk because, once milk cools down after boiling, fresh 
bacteria, falling into it from the air or obtaining access 
to it from pans or dishes not absolutely germ free, and 
finding the field clear, soon grow and multiply enormously, 
tending to bring about again very soon the former con- 
dition of a rich bacterial vegetation in a highly favorable 
soil or medium. The art of sterilization is based on the 
same principles, but avoids the necessity of repeated scald- 
ings by careful prevention of fresh invasions after the origi- 
nal bacterial population has been destroyed. 

There is no question as to the efficiency of sterilization of 
milk by thorough boiling or scalding, so far as the destruc- 
tion of germ life goes, but the process possesses certain im- 
portant disadvantages. In the first place, owing to the high 
temperature used and the time required, various chemical 
changes are wrought by which a peculiar flavor or "taste " 
is produced, known as a " cooked " taste, and this taste is 
disliked by many persons who enjoy the bland and character- 
istic flavor of raw milk. In the second place, there is evi- 



THE DISINFECTION OF MILK 287 

dence which cannot be disregarded that thoroughly cooked 
or sterilized milk is not as readily digested by some infants as 
is normal or even so-called "fresh" city milk. Considera- 
tions of this sort have led to attempts to avoid prolonged 
heating at a high temperature by the processes of " evap- 
oration," " pasteurizing," condensing by cold, etc., to which 
we shall briefly refer in the following paragraphs. For the 
sanitarian, however, the objections noted, while real and 
well worth avoiding, do not materially affect the great fact 
that sterilization of milk is an important sanitary safeguard. 
Because many dislike the taste of, and some do not thrive 
well when fed upon, sterilized milk, it is none the less true 
that by the use of sterilized milk infectious diseases, so far 
as these are conveyed by raw milk, can be altogether 
avoided. 

§ 23. — Pasteurization 

In view of the objections to scalded and sterilized milk 
which interfere with its practical usefulness by diminish- 
ing its popularity among adults and its usefulness for in- 
fants, various attempts have been made to destroy the 
germs, and especially any pathogenic or disease-producing 
germs it may contain, while yet preserving as much as pos- 
sible its normal flavor and its digestibility. The most im- 
portant of these attempts is that known as the process of 
" pasteurizing," so called in honor of Pasteur. Pasteur- 
izing consists in heating any fluid (milk, cream, wort, etc.) 
to such a temperature as has been described. In the case 
of milk the temperature preferred is about 158 to 160 F., 
and it is claimed that this temperature maintained for twenty 
to thirty minutes suffices to kill all disease germs and most 
germs of fermentation in milk, and yet produces but slight 
changes in its flavor or digestibility. On the other hand, 
it is claimed by many that its taste is in fact somewhat 
altered and its digestibility impaired, though certainly to a 
less extent than when more heat is used. The author some 



288 MILK SUPPLY AND THE PUBLIC HEALTH 

years ago stated his position in regard to pasteurized milk 
as. follows, and still holds essentially the same views : — 

" Most of the milk sold in Boston is at least twenty-four hours old 
when it reaches the consumer. Much of it comes by rail from distant 
parts of Massachusetts, and even from other states. The consumer is, 
as a rule, totally ignorant of the place of origin of the milk which he 
buys, and equally so of the conditions — whether wholesome or unwhole- 
some, sanitary or unsanitary — of the farms on which the milk is pro- 
duced. 

" It would be of great advantage to consumers and producers alike 
if the milk farms tributary to a great city could be visited and inspected ; 
and it would add materially to the keeping qualities of milk (and there- 
fore to its economic value) if it could be carefully pasteurized before 
beginning its journey to the city. 

"Moreover, inasmuch as typhoid fever is often disseminated by milk 
and as there is reason to believe that milk is a vehicle for some other in- 
fectious diseases, such as tuberculosis and possibly scarlet fever and 
diphtheria, pasteurization, which is a safeguard against the conveyance 
of such diseases by milk, commends itself to every sanitarian. 

" Pasteurization also postpones the decomposition of milk and its 
consequent staleness by destroying germs which produce souring, and 
thus helps to keep it in this respect nearer to the ' normal ' required by 
infants." 

§ 24. — Condensation 

The condensing of milk when it is effected by prolonged 
boiling under atmospheric pressure is a great, and probably 
an absolute, safeguard against infectious diseases conveyed 
by milk. Such " condensed " milk is, however, open to 
the same objections as sterilized milk, and probably in even 
greater degree. Condensed milk is, however, safe to use so 
far as infectious diseases are concerned ; and in spite of the 
objections urged against, and which certainly require it to 
be used intelligently, it is a valuable adjunct to the sanitary 
food supplies of mankind. When milk is condensed at a 
lower temperature by the aid of the vacuum pan, as is 
often the case, it is probable that the product is almost if 
not quite equally safe from a sanitary standpoint, and some- 
what less objectionable from the purely hygienic point of 



CONDENSED MILK 289 

view. Such milk, less condensed, is sometimes known as 
"evaporated " milk, and is highly valued by some. 

An ingenious process proposed for condensation is that 
in which cold instead of heat is used for condensing, the 
water being removed from the milk by freezing. In this 
process advantage is taken of the fact that water in freezing 
tends to crystallize pure, by allowing milk, from which the 
cream has been removed (separated or skimmed milk), to 
freeze over in shallow pans subjected to intense cold. The 
thin skimming of ice constantly forming at the surface 
is broken up by rakes, and fresh layers form ; these are 
broken up in their turn, and so on, until the whole mass 
becomes a magma of ice crystals and unfrozen milk. The 
mass is then centrifugalized ; and the milk, thus readily 
separated from the ice, is returned to the pans for further 
freezing. At last a condensation of sixty to eighty per cent 
is attained, and afterward to the thickened fluid cream is 
added in proper proportions, so that when diluted with two, 
three or four times its own volume of water, a product is 
said to be obtained closely resembling fresh milk, having no 
"cooked" odor, and keeping its digestibility unimpaired. 
This process has not yet been perfected, but it is cer- 
tainly ingenious in principle. 

§ 25. — Modified Milk 

The so-called " modified " milk is important rather 
from the hygienic than the sanitary point of view, but 
yet deserves mention and commendation inasmuch as 
its fundamental requirement is clean, pure, sanitary or 
normal milk. This having been secured, the process of 
" modification " consists in so adding to, or subtracting 
from, its normal ingredients that it shall contain speci- 
fied amounts of sugar, fat, salts, etc., such as may be 
desired for particular cases or ordered by physicians in 
their treatment of disease or other abnormal conditions. 



290 MILK SUPPLY AND THE PUBLIC HEALTH 

In connection with establishments supplying " modified" 
milk, dairies of a superior order are not infrequently main- 
tained, and to a brief consideration of sanitary dairies in 
general we may now proceed. 

§ 26.— Model (Sanitary) Dairies 

With the advancement of sanitary science and an appre- 
ciation of the sources of danger in the milk-supply indus- 
try, there have been established here and there dairies in 
which every possible endeavor is made to provide, for 
those willing to pay for it, milk as safe and as normal as 
it is possible to procure by the use of the most enlightened 
methods. One or more of these may generally be found 
near every large American city, and they are deserving of 
the highest commendation and the fullest support from 
sanitarians, because they fill an important place and do 
a most useful work, while at the same time they serve as 
living, and generally prosperous, examples of proper sani- 
tary standards of practice in what is still far too com- 
monly a primitive industry, primitively conducted. 

§ 27. — The Cows 

These, in model dairies, are carefully chosen and of good 
breeds. Care is taken to ascertain, as far as possible, that 
they are healthy and vigorous, not only by veterinary 
examinations when they are added to the herd, but by 
similar examinations regularly and often repeated. 

§ 28. — The Stable, etc. 

The stable is so arranged as to have abundant space, 
light, fresh air and quick and easy removal of urine and 
droppings. The bedding is kept clean and sweet, food and 
drink are ample and carefully chosen, the period of lacta- 
tion is not unduly prolonged, the cows are groomed very 






MODEL OR SANITARY DAIRIES 291 

much as valuable horses are, they are protected to some 
extent from the irritation of insects, they are given space 
out of doors for exercise in winter, and pasturage, with 
good water in abundance and sufficient shade, in summer. 

§ 29. — The Milkers 

The milkers must be of a grade high enough to appre- 
ciate, at least in some degree, and to be willing cheerfully 
to cooperate in, the general sanitary plan. They must 
be willing to wash their hands before beginning to milk. 
They must in some cases be ready to wear, while milking, 
uniforms of white, clean cloth. They must be willing, 
before beginning to milk, to wash the cow's udder, if this 
is necessary, or to wipe it and the teats with a clean, damp 
cloth. They must be ready to decline to use pails, cans, 
strainers, etc., not strictly and scrupulously clean. Above 
all, they must be ready to refrain from " handling " the 
milk in any way, if need be, when in themselves or their 
families there is even a suspicion of any infectious disease, 
such as scarlet fever, diphtheria, typhoid fever or the like. 
These are high qualifications, but they are not too high. 
Persons working over and about milk should have quali- 
fications similar to those of a trained nurse, namely, intel- 
ligence, faithfulness, readiness to obey orders, some 
technical skill and a high devotion to duty. Like the 
nurse, they should be always mindful of the fact that care- 
lessness, unfaithfulness or disobedience on their part may 
result in the gravest disaster. 

It follows, as a matter of course, that such service must 
be well paid. It follows, also, that for all the care speci- 
fied, — and even more is required than is here set down, — 
for the careful owner and manager, the veterinary doctor, 
and their various aids and appliances, large sums must be 
paid. Hence, those who enjoy the benefits of such sanitary 
dairies must be prepared to share the burdens of their 



292 MILK SUPPLY AND THE PUBLIC HEALTH 

support. Milk sold from model dairies commands, and 
deserves to command, a higher price than that from prim- 
itive establishments carelessly conducted. There is not 
the smallest doubt, however, that impure milk is dear at 
any price, precisely as are impure water, impure air and 
other foods or necessaries of life. 



§ 30. — The Outlook for Improved Milk Supplies 

There is a very general, encouraging and wholesome ten- 
dency on the part of the public to demand a better milk 
supply. Already there are many signs that the time has 
gone by when it will be considered sufficient for a board 
of health to secure protection of the public against fraud 
due to adulteration of milk with water, or falsification, of 
one sort or another. It is a curious commentary on the 
subject that in Massachusetts many of the official inspec- 
tors of milk are in no way connected with the boards of 
health in their respective cities or towns. This, wherever 
it exists, should be changed, so that the sanitary protec- 
tion of milk shall be, where it belongs, in the hands of 
those charged with protection of the public health. 

Note. Many valuable suggestions upon this subject may be found 
in a paper by R. A. Pearson, M.S., entitled "Market Milk : a Plan for 
its Improvement? [Seventeenth Annual Report, Bureau of Animal 
Industry, (1900).] 



CHAPTER XII 

ON CERTAIN UNCOOKED FOODS (MEATS, OYSTERS, FRUITS, 
VEGETABLES, ETC.) AS VEHICLES OF INFECTIOUS DIS- 
EASE. THE SANITARY SIGNIFICANCE OF COOKERY 

Infected water and infected milk are perhaps the 
commonest and the most dangerous vehicles of infectious 
disease. They are, however, by no means the only vehi- 
cles, certain other foods, such as uncooked meat, oysters 
and vegetables, serving readily enough as the carriers of 
infectious particles. The discovery of this fact was first 
made in the case of uncooked meat, the muscles of swine 
having been found in i860 to have served as a vehicle of 
a parasitic worm, Trichina spiralis. Numerous epidemics 
of trichinosis have been studied since that time, and this 
disease is now well known to be caused by the consumption 
of the uncooked flesh of infected hogs. Special measures 
of prevention are now established in many countries against 
this disease, but the best preventive is the simplest, namely, 
thorough cooking of all such products — pork, ham, sau- 
sages and the like — as are derived from hogs. 

§ 1 . — Trichinosis or the Pork- Worm Disease 

This disease, which is characterized by intense inflam- 
mation and irritation, with high fever, soreness, muscular 
paralysis, dropsical swellings and, in severe cases, death 
in from five to fifty days, is now known to be caused by a 
minute cylindrical worm barely visible to the naked eye, 
and therefore entitled to be called a micro-organism, which, 
in the larval state, inhabits the muscles of man, swine, dogs, 

293 



294 RAW FOODS AS VEHICLES OF DISEASE 

cats, rats, mice, rabbits and guinea-pigs, and many other 
animals, and in the mature state lives in the intestines of 
the same animals. The male is much smaller than the 
female, and when mature measures only about ^ of an 
inch in length. The female is stouter and longer, measur- 
ing when mature about J of an inch. The eggs are about 
T2V0 °^ an ^ ncn m length. The young trichinae, like young 
tapeworms, occur embedded in the muscles of the hog and 
various other animals and man ; but, unlike the young 
tapeworm, the young trichinae are so small as to be quite 
invisible to the naked eye, and millions of them may exist 
in the flesh of a pig without producing any unusual appear- 
ance in the meat sufficient to attract the attention, unless 
with a microscope. When first introduced into pork or 
human flesh, the little worms are free and coiled up among 
the muscular fibres, but after four or five weeks they be- 
come enclosed in minute whitish, elongated oval or round- 
ish cysts or capsules, due to the inflammation and irritation 
that they cause by feeding and living. After a year or 
more these cysts become calcified, and are then visible to 
the eye as minute specks scattered through the muscles. 
When enclosed in the cyst, the worms become dormant, 
and they may live for years, and even some time after the 
death of their host. They can do no further harm unless 
swallowed by man or some other animal. Each cyst con- 
tains a little slender worm about J^ of an inch long, coiled 
up in two or three turns. 

If pork or other flesh containing these worms — either 
free or enclosed in cysts — be eaten by man, they become 
liberated in the stomach, and, entering the intestine, attach 
themselves to its soft lining ; and there, surrounded with 
abundant food, they grow very rapidly and become mature 
in about two days. Here the females live long enough to 
produce broods of from five hundred to one thousand young 
worms each. As one ounce of pork sometimes contains a 
quarter of a million or more of the worms, it is not surpris- 



TRICHINOSIS OR THE PORK-WORM DISEASE 295 

ing that the millions of adult worms and their offspring, 
sometimes resulting from a single meal of raw swine flesh, 
should by their presence produce great irritation and inflam- 
mation of the intestine and violent diarrhoea and vomiting, 
which are often the first symptoms in severe cases. 

The young worms, almost as soon as they are born, 
begin to eat or force their way through the membranes of 
the intestine into the minute blood-vessels and other organ- 
isms, thus vastly increasing the irritation. Eventually they 
become diffused through the entire system, and are found 
most abundantly in the groups of muscles nearest the 
abdominal cavity. 

The duration of the disease, like its severity, is in direct 
proportion to the number of living trichinae swallowed, and 
varies from two weeks to three or four months. Even in 
many comparatively mild cases the suffering is intense, and 
the recovery slow and tedious. When all the worms have 
become lodged in the muscles and enclosed in cysts, the 
direct symptoms cease, and, if the strength of the patient 
has been kept up, recovery is probable. 

Persons in robust health may be able to survive the 
attack of half a million or more of these flesh-worms, and 
recover ; but there is a limit to all human endurance, and 
the numbers often contained in the muscles of man or the 
lower animals killed by them are almost incredible. In 
some very severe cases the numbers contained in human 
bodies have been estimated by reliable authorities to be 
as great as forty or sixty millions. 

The cysts containing trichinae were first observed in 
human muscles in 1822; but the worms from similar cysts 
were first named and described by Owen in 1835. They 
were, however, only regarded as anatomical curiosities of 
no practical importance until i860, when Zenker proved 
that they are capable of producing the severe and often 
fatal disease now well known under the name of trichinosis, 
but which had been previously, as it probably often is still, 






296 RAW FOODS AS VEHICLES OF DISEASE 

confounded with typhoid fever, inflammatory rheumatism, 
or rheumatic fever, poisoning and various other diseases. 



§ 2. — Infected Pork as a Vehicle of Trichinosis 

A few epidemics of trichinosis may be briefly referred 
to: at Hettstadt, in 1863, the flesh of one pig infected 
135 persons, 20 of whom died. Many other similar epi- 
demics have occurred in Germany. The following may be 
cited in the United States: at Marion, la., in 1866, a man 
named Bemis and eight members of his family ate under- 
done and raw ham, and were immediately taken sick. 
Three died, and the others narrowly escaped. Autopsy 
showed about 100,000 worms to a cubic inch of muscle in 
one of those who died. At Dubuque, la., two families 
were attacked. In one, five persons died ; in the other, 
five or six. A case is cited by Dr. Horr in this connection 
in which the mother of a family ate of the central under- 
done part and took the disease, while those who ate the 
better cooked outside parts escaped. At Springfield, Mass., 
February, 1867, a man and his family ate of raw ham, and 
all seven members were attacked more or less severely 
according to the amount eaten. A daughter died, and the 
father had a long and very dangerous illness. At Albany, 
N. Y., in January, 1869, two boys ate of raw ham, and 
were infected. The rest of the family ate of the same 
ham cooked, and escaped. At Rome, N. Y., December, 
1868, a man and his family, nine persons in all, ate raw 
smoked and dried sausages. The father, son and two 
daughters died before January 15. The sausages and salt 
pork were examined and found to be full of trichinae, as 
were also the muscles of those who died. In New York 
City, January, 1869, eight cases occurred in a boarding- 
house from eating sausages. Two of the victims died in 
the New York Hospital, and others were dangerously sick. 
It is interesting to note that the physicians in two hospitals 



EPIDEMICS OF TRICHINOSIS 297 

mistook these cases at first for typhoid fever, and only 
discovered their mistake after one death had occurred. 

The means of prevention in the case of trichinosis is 
very simple, namely, thorough cooking, and the rarity of 
the disease among people who avoid raw or underdone 
swine flesh in any of its varieties establishes the efficacy 
of the remedy. 1 

§ 3. — The Question of Infection by Tuberculous Meat 

Of late years there has been widespread interest in the 
question of tuberculous meat. There is very little doubt 
that the germs of tuberculosis frequently occur in the 
muscles of cattle, cows, calves and other animals, and the 
possibility of their surviving the ordinary operations of 
cookery must be allowed unless these operations are 
thorough. In Germany, and to some extent in other coun- 
tries, inspectors are employed to prevent the sale of meat 
obviously tuberculous. There are very few facts available, 
however, as to the precise dangers of such meat, and it is 
difficult to resist the belief that excepting in the use of 
underdone infected meat there is little danger of infection 
by tuberculosis from this source. 

§ 4. — Raw Oysters as a Vehicle of Infectious Disease 

The possibility of infection by raw oysters grown in 
sewage-polluted waters had been recognized by sanitarians, 
but not much emphasized, previous to 1894. In that year, 
however, the attention not only of sanitarians but of the 
whole world was drawn to the subject by a remarkable 
epidemic of typhoid fever among certain students of 
Wesleyan University, in Middletown, Connecticut, who had 
attended a college fraternity banquet on the 12th of October, 
and had there eaten raw oysters which were afterward 

1 § 1 and § 2 are summarized from a Report prepared by Professor A. E. 
Verrill of Yale University for the State Board of Agriculture of Connecticut. 






298 RAW FOODS AS VEHICLES OF DISEASE 

proved to have been derived from sewage-polluted and 
probably typhoid-infected oyster-beds. A careful investi- 
gation was made at the time by Dr. H. W. Conn, Professor 
of Biology in Wesleyan University on behalf of the State 
Board of Health of Connecticut, whose report may be 
found in the Seventeenth Annual Report of the State 
Board of Health of Connecticut for 1894, and also as 
Appendix Number Three of the Supplement to the twenty- 
fourth Annual Report of the Medical Officer of the Local 
Government Board for 1894- 1895, entitled " Oyster Culture 
in Relation to Disease," p. 152. London, 1896. This 
epidemic was so remarkable, so ably investigated by Pro- 
fessor Conn, and forms so complete a demonstration of the 
efficiency of raw oysters as vehicles of disease, that no 
apology need be made for giving a somewhat extended ab- 
stract of the original paper. The author says very truly : — 

" A more typical example of an outbreak of typhoid due to a single 
source of infection has hardly been found in the history of medicine, and 
the example furnishes a demonstration of a new source of danger for 
this disease. 

" The use of raw oysters has before been suggested as a possible 
source of the spread of the disease. The readiness with which these 
absorb water, and the fact that they not infrequently lie in positions 
where contamination with sewage appears to be possible, has led to 
their being suspected in several cases. It has hitherto, however, not 
been possible to trace any distinct epidemic to them with anything like 
demonstrative evidence. The conditions which have occurred at Wes- 
leyan have, however, been exceptionally well adapted to point out this 
connection. Indeed, if one had planned beforehand a series of experi- 
ments designed to prove the possibility of oysters as distributing typhoid, 
it would hardly have been possible to have devised a more satisfactory 
series of conditions than those which have obtained in this outbreak at 
Wesleyan." 

§ 5. — An Epidemic of Typhoid Fever traced to Infected 

Oysters. 

About October 20, 1894, several students were seized 
with a mild form of sickness accompanied by slight fever, 



A NOTABLE EPIDEMIC OF TYPHOID FEVER 299 

which was not at first regarded as of much importance. 
The cases increased in number, some became more severe, 
and after about a week it became evident that a few, at 
least, were suffering from typical typhoid fever. New 
cases continued to appear until, by November 1, there 
were more than twenty. After November 1 the cases 
fell off, although one appeared as late as November 9. 
In all, there were twenty-five cases — twenty-three of well- 
defined typhoid, of which thirteen were very severe. Four 
of those attacked died. 

Investigation was begun on November 4. Suspicion fell 
at first upon certain wells on the college campus, but these 
were excluded, chiefly on the ground that they were used 
by large numbers of townspeople as well as by college 
students, and that no typhoid had appeared among the 
townspeople. 

No common bond was at first discovered among the vic- 
tims of the disease, some of whom lived in different dormi- 
tories or club-houses, and others in private houses in the 
town. Nor did the persons affected board at the same 
tables. Besides, Wesleyan University is a coeducational 
institution, and it was early observed that the young 
women in the University — about fifty in number — were 
wholly exempt. Closer investigation showed that, with 
three exceptions, all the cases attacked belonged to three 
fraternities, and that within these some extremely potent 
source of infection had been active. Attention was thus 
concentrated upon these fraternities and their club-houses. 

As is usual in such cases, the plumbing was carefully 
examined, and in two of the three houses it was found to be 
new and unexceptionable. Attention was next fixed upon 
the boarding clubs within the fraternities. The water, the 
ice and the milk were all considered, but excluded as 
sources of infection, from the fact that they were shared in 
common by other fraternities or by the townspeople. Simi- 
lar circumstances excluded cream, ice-cream, butter, fruit, 



300 RAW FOODS AS VEHICLES OF DISEASE 

and other articles as probable sources of the disease. So 
difficult and far-reaching was the inquiry, that it was even 
suggested that certain new foot-ball suits might have been 
infected, thus giving rise to the disease ; but only a few of 
the men who had used the suits were found to be suffering 
from the disease, while several of the sick men had never 
touched them. There was also no evidence of secondary 
infection which could explain the outbreak, and particu- 
larly as there were no early cases of fever which could 
have served as the sources of such secondary cases. The 
first case appeared about October 20, and within a week 
from that time at least fifteen other cases had made their 
appearance. 

These facts, of course, indicated plainly a common source 
of infection, and made it possible to believe that any of 
these was the source of all the others by ordinary contagion. 

Moreover, there was a very small amount of typhoid in 
the city, and — 

"In short, all the lines of investigation upon the relations of the stu- 
dents, the conditions of their fraternity houses, and the tables at the 
fraternity houses led to negative results, giving no point of common 
union between the three fraternities in question, which was not shared 
equally by the four other fraternities and the ladies in the college, and 
equally by the citizens in town." 

A study of the dates on which the disease had appeared 
threw suspicion upon a series of fraternity suppers held at 
the society initiations of new members upon the 12th of 
October, and this suspicion was strengthened by the ex- 
planation which it appeared to offer of one of three cases 
which had appeared among members of the University not 
in any of the three fraternities. This person had attended 
the initiation banquet held by one of these three clubs, but 
had not boarded with them either before or afterward. Ex- 
amination of the menu of the banquets excluded nearly all 
articles of food, such as water, ice, milk and cream, ice- 
cream, fruit and salad, as possible sources. The celery 



AN EPIDEMIC TRACED TO A BANQUET 301 

used in the salad was at first regarded as a source of pos- 
sible danger. It had been bought from different dealers, 
but these dealers obtained it all from the same grower, and 
he had occasionally washed his celery in the water of the 
Connecticut River — a somewhat suspicious circumstance. 
Further inquiry, however, showed that the same dealer 
supplied nearly all the celery used in Middletown, and had 
consequently furnished hundreds of families from the same 
source. 

As a result of the closest inquiry in regard to every arti- 
cle of food or drink used at the banquet, there were found 
to be only three common to the three suppers ; namely, 
ham, a small amount of fruit, and raw oysters. The ham 
was readily excluded, both because it had been cooked and 
because the same dealer supplied other fraternities. More- 
over, there was no reason to suppose that it had been con- 
taminated. The fruit had been shared by other fraternities 
and by townspeople, and was therefore excluded. 

" As soon as attention was turned to the oysters, however, the prob- 
lems began to be solved at once. To those engaged in the investiga- 
tion, one of the most striking phenomena was the quickness with which 
the puzzling questions were answered as soon as they were studied in 
the light of the oysters as a possible source of contamination. It was 
found that the ladies in the college did not hold any special supper on 
the evening of October 12, nor eat raw oysters, either then or subse- 
quently. It was found that of the other four fraternities, two did not 
use oysters at all at the initiation suppers ; one obtained oysters from 
Hartford dealers, who obtained them from a different source than the 
Middletown dealers. The fourth used the oysters from the same source 
as the fraternities in question, but had used them cooked, while the 
three fraternities that had suffered from typhoid had eaten the oysters 
on the half-shell, and consequently raw. As soon as it was conceived 
that the oysters might be the cause of the trouble, one more of the ex- 
ceptions above mentioned was explained, for one of the students belong- 
ing to another fraternity, who had suffered from a mild fever, stated that 
at about the time of the initiation banquets he had eaten raw oysters in 
the oyster dealer's store in town. This, of course, made it possible to 
bring this case within the same source of infection. 

" Inquiry as to the use of the oysters in town revealed nothing which 



302 RAW FOODS AS VEHICLES OF DISEASE 

relieved the oysters from blame. Quite a number of families were sup- 
plied from the same lot of oysters, but so far as could be learned, only 
one family bought them to eat raw, and this family had subsequently 
moved from town and had been lost track of. Further facts concerning 
this case will be mentioned later. The attendants in the oyster dealer's 
store had probably eaten of the raw oysters, inasmuch as they did fre- 
quently do so, although they had no definite recollection of this particu- 
lar lot. Neither of them had experienced any evil results. This, of 
course, is not surprising, since ordinarily not much more than ten per 
cent of those exposed to typhoid fever suffer from the exposure ; and 
even among the students at the banquet not quite one in four took the 
disease. If the people in town who ate the oysters had not generally 
cooked them before eating them, a larger number of cases would have 
been expected." 

The oysters at the banquets were served on the half- 
shell as a course at the beginning of the supper. Careful 
inquiry was made as to how many persons had actually par- 
taken of the oysters, and direct connection with the oysters 
was traced in all cases except one, this one student being 
unable to remember that he partook of them. He did, how- 
ever, attend one of the banquets. The four who died were 
among those who partook of the oysters. 

There were also present at the banquets a number of 
persons not students of the college. Among them were a 
number of alumni, and five students from Yale University. 
Reports were obtained from twenty-four of the alumni who 
ate of the oysters. Among them were several cases of 
slight illness, chills, diarrhoea, weakness, and the like which 
appeared at about the same time that the typhoid appeared 
in Middletown. These may or may not have had some 
connection with the infection. In addition, four cases of 
genuine typhoid fever appeared, most of which had been 
pronounced to be typhoid before there was any knowledge 
of connection with cases at Wesleyan University. None 
were severe, but all appeared simultaneously with the cases 
at Wesleyan. 

Of the five Yale students who attended the banquet, two 
developed typhoid fever, though at a rather late date. 



TYPHOID FEVER AND RAW OYSTERS 303 

These facts demonstrated that the cause of the infection 
was to be sought in the initiation suppers. The cessation 
of new cases at the end of four weeks, and the appearance 
of at least six cases among visitors who came to the ban- 
quets and went away immediately afterward, — 

"are sufficient in themselves to indicate beyond peradventure that 
the initiation suppers are to be regarded as the source of infection. 
And when, further, it is seen that only one article of food or drink was 
used in common by these three societies, that was not used equally by 
the other fraternities in college and by people in town in general, it 
becomes equally certain that this one article of food must have been the 
source of infection. 

" Inquiry showed that the oysters in question had been taken from 
deeper water in Long Island Sound, and had been brought [to Fair 
Haven, Connecticut] into the mouth of a creek known as Quinnipiac 
River, and allowed to lie in fresh or brackish water a day or two 
for fattening before they were taken out of the water and sent to the 
consumers. During this period of fattening, the oysters are known to 
absorb fresh water and to swell up and become quite plump. The 
object of this treatment is partly to thus ' fatten ' the oysters, and partly 
to wash them. Close to the oyster beds where this fattening occurs 
are the outlets of a number of private sewers. At a distance of some 
three hundred feet from the beds where the oysters were fattened was 
an outlet from a private sewer from a house in which were two cases 
of typhoid fever. The patients were a lady and her daughter. The 
cases were severe, the lady dying on the 21st of October, and the 
daughter convalescing only after five weeks 1 sickness. . . . The dis- 
tance from the outlet of the sewer to the oyster ground was . . . 
between 250 and 300 feet. When the grounds were surveyed, it was 
further noticed that at the rising tide an eddy was found to be setting 
along the shore from the region of the sewer outlet up stream, in the 
direction of the oyster beds. This condition would plainly make it 
possible for typhoid contaminations from the sewer to be carried to the 
oysters. 

" Examination as to the dates of the cases of typhoid occurring in 
the house on the sewer showed that the two persons in question were 
taken sick at just about the time that the oysters sent to Middletown 
were collected. The oysters were sent to Middletown on October 10, 
and the doctor was first called to these cases on October 11. The 
period of incubation of typhoid fever is known to be somewhat variable, 
and had certainly existed some time before the doctor was called. 



304 RAW FOODS AS VEHICLES OF DISEASE 

From the fact that when the doctor was called the lady was suffering 
from a severe chill and fever, it was plain that the conditions were such 
that infection through the sewer might naturally have taken place at 
least for several days prior to the period of the first visit of the doctor ; 
for during this incubation period the persons may appear well, and yet the 
presence of the typhoid germs render their excreta infectious. Indeed, 
the danger might be even greater at this stage than subsequently, since 
as soon as the disease is plainly indicated nurses will be pretty sure to 
disinfect the excreta and thus diminish the danger. This would bring 
the time of possibility of infection at just about the period when the 
oysters sent to Middletown were collected." 

Special investigations made by Dr. Charles J. Foote, of 
the Yale Medical School, showed that typhoid bacilli 
forced in between the shells of oysters taken from the 
creek were found alive and capable of growth at the end 
of forty-eight hours, and — 

"this is all that is required to account for the outbreak at Middle- 
town." 

In connection with an outbreak of typhoid fever at 
Amherst College at the same time as that of Wesleyan, it 
was learned that Fair Haven oysters had also been sent to 
Amherst. In the latter institution a similar banquet was 
held upon the same evening, October 12, at which raw 
oysters were served, and of six students who afterward 
suffered from typhoid fever all but one ate raw oysters on 
or about that date. It was not discovered whether or not 
the oysters came from the same dealer in Fair Haven, but 
the suspicion was strong that such was the fact. 

One of the most interesting and instructive circum- 
stances connected with this epidemic remains to be stated. 
A young man whose home was in Boston, himself a stu- 
dent at Harvard University, came down with typhoid fever. 
His case at first seemed utterly inexplicable. It happened 
that his father was a physician and for a time no reason- 
able explanation could even be thought of. It proved, how- 
ever, that about two weeks before he fell ill he had gone 
home with a classmate whose family lived in Middletown, 



RAW SHELLFISH 



305 



and inquiry showed that he was attacked, after he had 
returned to his home in Boston, at precisely the same time 
as the Wesleyan students, and that he had eaten raw 
oysters while in Middletown. It further appeared that the 
oysters which he ate came from the same dealer as those 
with which the Wesleyan banquets were supplied, and that 
he had, in fact, partaken of the one lot which, as was 
mentioned above, had been sold by the Middletown dealer 
to a family in Middletown to be eaten raw. 

§ 6. — Dangers of Infection from Raw Shellfish 

Professor Conn's remarks upon this subject are instruc- 
tive : — 

" It is a very important point to determine to how great a danger 
the public is exposed from raw oysters. Is the distribution of typhoid 
by oysters a rare incident, or is it a constant and considerable danger ? 
These questions are being everywhere asked. Upon this matter at 
present little can be given beyond personal opinion. But the question 
is such a vital one that a word of personal opinion here may perhaps 
be pardoned. 

" In the first place it appears evident that the public opinion at first 
exaggerated the amount of the danger. The lot of oysters sent to 
Wesleyan was very thoroughly infected, but there is no good evidence 
as yet that other lots of oysters from the same place were equally dan- 
gerous. The oysters sent to Amherst were probably also infected, but 
these probably belonged to the same lot as those sent to Middletown. 
Beyond this it has as yet been impossible to trace with certainty other 
instances of typhoid to the Fair Haven oysters. If it were true that all 
the oysters fattened at the same place were similarly infected, it would 
be expected that quite a number of cases of the disease should be 
traceable to the oysters. In New Haven especially, where the Fair 
Haven oysters are used largely, there would presumably have been 
found an exceptionally large amount of typhoid. There has been some 
considerable typhoid in the city during the months of October and 
November, and in a few cases it has been presumably traced to oysters 
as shown elsewhere in the report of the State Board of Health. But 
there is hardly the amount that would be expected if the oysters were 
all subject to a contamination such as that which affected those sent to 
Middletown. Indeed, the consideration of the conditions at the oyster- 
x 



306 RAW FOODS AS VEHICLES OF DISEASE 

beds would lead to the belief that the contamination of the oysters 
would be exceptional. Where the oysters were placed near the mouth 
of a small sewer, and when this sewer came from a house containing 
typhoid patients, the danger of their contamination would be at its 
maximum. Should they chance to be placed near the mouth of a large 
city sewer, the danger, though a more constant one, would be much less 
likely to produce any considerable contamination of a large lot of oys- 
ters, since the typhoid material would be mixed with so much water 
as to distribute it widely and in a very dilute condition. Only an 
occasional oyster would thus be infected. At Fair Haven, however, 
when a proper eddy brought the material from the vicinity of the sewer 
toward the oysters, the chances were good for the whole lot to become 
infected. Perhaps oysters might lie in the same place many a time 
before and after, and not be injured thereby, because no eddy hap- 
pened at the right moment to sweep typhoid material in their direction. 
The danger from typhoid infection is, therefore, probably somewhat 
exceptional, even under the conditions existing. Where the oysters are 
fattened at a distance from sewers, the danger practically disappears ; and 
even where they are open to infection from large overflow of a city sewer, 
the danger is certainly less than in the fortunately exceptional case of the 
oysters in the vicinity of a private sewer containing typhoid excretions. 
" The extent of the danger will plainly depend very largely upon the 
question whether the typhoid germs actually grow and multiply in the 
oyster, or whether they simply remain alive there for some time. It 
may be that the oysters furnish a good culture ground for the typhoid 
germs, which grow rapidly when once within the shell. This would, of 
course, greatly increase the danger, for one lot in a fattening bed might 
infect others. On the other hand, it may be that the germs do not grow 
in the oysters, but that only such individual bacteria as find entrance 
remain alive. In this case the infectious material would be found only 
in the juices in the shell and adhering to the outside of the shell. The 
danger would, of course, be much less. Which of these two conditions 
represents the facts cannot at present be stated. It is hoped that 
experiments now in progress will settle the matter. But, according to 
either view, oysters may serve as a means of transportation of typhoid 
wherever they are fattened in the vicinity of sewers ; and wherever they 
are placed in the mouths of fresh-water streams for this fattening process, 
there will always be the chance of contamination from sewage. Few of 
the fresh-water streams in the vicinity of our large cities fail to have 
sewage emptying into them. While, then, we cannot determine the 
extent of the danger, and while, in the opinion of the writer, the dan- 
ger is not very great, it must be recognized as a danger. Probably not 
a few of the obscure cases of typhoid which develop each fall shortly 



SHELLFISH AS VEHICLES OF INFECTION 307 

after the oyster season opens, and which cannot be traced to any source, 
may be due to contamination through oysters. It is, of course, impos- 
sible to determine the truth of this suggestion ; but now that the possi- 
bility has been pointed out, we may hope that our health boards may, in 
future years, be able to determine the real extent of the danger. One 
thing is sure : the public health is placed in jeopardy when oyster 
dealers, for the sake of producing plumpness, place oysters in the 
mouths of fresh-water creeks in close proximity to sewers. It is hoped 
that one result of the epidemic at Wesleyan will be to lead to greater 
care in this direction, both on the part of the oyster dealers themselves, 
whose business will certainly be greatly injured by the repetition of such 
outbreaks of typhoid as that at Wesleyan, and on the part of our boards 
of health, who have in their keeping so much of the public weal." 

§7. — English and French Opinion in Regard to Dangers 
of Infectious Disease from Raw Oysters 

Roused by the remarkable American epidemic which 
has just been described, the Local Government Board 
instituted a careful investigation of the conditions under 
which oysters and certain other mollusks are cultivated 
and stored in Great Britain ; and a valuable report, bring- 
ing the whole subject up to date (1896), appeared as a 
supplement to the report of the medical officer of that 
Board for 1894- 1895. This contains a report by Dr. 
H. T. Bulstrode on " The Conditions under which Oysters 
and Certain Other Edible Mollusks are cultivated and 
stored along the Coast of England and Wales " ; a report 
by Dr. Klein on " Certain Bacteriological Researches," in 
connection with the same subject; a copy of Professor 
Conn's report, already quoted in the preceding paragraphs, 
as well as extracts from the " Proceedings of the Academy 
of Medicine of Paris relating to the Spread of Disease 
through the Agency of Oysters." 

§ 8. — The Contamination of Oyster-beds by Sewers 

The concluding remarks of Professor Conn, in his 
report on the " Epidemic of Typhoid Fever caused by 



308 RAW FOODS AS VEHICLES OF DISEASE 

Raw Oysters at Wesleyan University," indicate, conclu- 
sively and in detail, the dangers to which oyster-beds are 
subjected when so placed as to be overflowed and con- 
taminated by sewage. The English report referred to in 
the preceding paragraph furnishes numerous instances of 
the growing or storage of oysters under unsanitary condi- 
tions; and those charged with the conservation and pro- 
motion of the public health should keep in mind the 
possibility of such contamination, as well as the necessity 
for its prevention. No extensive investigation of this sub- 
ject has as yet been made in the United States ; but there 
is good reason to suspect that if such examination should 
be made, it would reveal, in many cases, the existence 
of unsanitary conditions in connection with the oyster 
industry. 

One of the most interesting corollaries of the facts now 
in our possession in regard to the dissemination of typhoid 
fever by oysters is the explanation which it furnishes of 
certain so-called " sporadic cases " of typhoid fever hitherto 
inexplicable. Whether or not the same facts will suffice 
to account, in part, for that excess of typhoid fever which 
is characteristic of many American communities over simi- 
lar communities in the Old World, is unknown ; but it is 
difficult to resist the feeling that such may be, to some 
extent, the fact. The whole subject of the dissemination 
of disease through uncooked foods requires further study 
and elucidation. 

§ 9. — Fruits, Vegetables, Ice-cream, etc., as Vehicles of 
Infectious Disease 

Inasmuch as any uncooked food material may be pol- 
luted, and, if eaten in this condition, may become the source 
of disease, it is easy to see how berries, such as straw- 
berries, grown and lying on earth which has been fertil- 
ized with night soil, or mulched with infected manure; 
raspberries, cherries, apples, grapes, and similar fruits; 



POSSIBLE ORIGIN OF SOME "SPORADIC n CASES 309 

vegetables, such as lettuce, celery, radishes, onions, water- 
cress and the like, if eaten raw, or without adequate clean- 
ing, may readily convey the germs of infectious disease to 
the consumer. There can be little doubt that the common 
American practice of buying fruit at fruit-stands, or from 
passing venders on the streets or in railway trains, may be 
a ready means for the distribution of infectious disease. 
When we reflect that not infrequently the fruit shop is 
also, to a greater or less extent, the home of the vender's 
family; when we reflect on the frequent picking over of 
berries, cherries, apples, and the like, by persons whose 
hands and whose personal habits may be far from clean; 
when we add to this the exposure of the fruit to dust and 
dirt from various sources ; and when, finally, we remember 
that buyers of such fruits or vegetables often devour them 
on the spot without stopping to make sure that they are 
clean, we can readily see that in such food materials thus 
exposed, and eaten without having been sterilized by 
cookery, we have a ready means for the dissemination of 
infectious disease and an explanation of " sporadic " cases. 

On the other hand, it is reassuring to note that certain 
fruits, such as oranges and bananas, although usually eaten 
raw, are effectively protected by their skins, which are 
invariably rejected, leaving only the clean and sterile 
interior to be eaten. 

As to sugared figs, dates, and similar preserved fruits, 
while there is probably less danger, it must not be over- 
looked that if these have been prepared by unclean or 
infected persons, they also may become vehicles of the 
germs of infectious disease. 

The dangers connected with the consumption of ices and 
ice-creams are probably real. After making all possible 
allowance for those cases of ice-cream poisoning which may 
have been due to metallic poisons derived from the freezer 
or other utensils, it must be admitted that the ice, the 
water, and especially the milk, used are liable to be sources 



310 RAW FOODS AS VEHICLES OF DISEASE 

of disease in ices or ice-creams. Bacteriological examina- 
tions of ice-cream are by no means reassuring, large num- 
bers of germs often being present, and ices and ice-cream 
may conceivably do harm either by the bacteria which they 
contain or by their chemical products (toxines or ptomaines). 

§ 10. — The Sanitary Significance of Cookery 

Nothing is more certain in sanitary science than that 
cookery, which by the use of heat destroys parasites 
(including bacteria), is of the very highest hygienic value. 
If we may accept Charles Lamb's celebrated account of its 
discovery and general introduction, these were due more 
to the appetizing flavors which it develops than to anything 
else. To-day, however, the sanitarian recognizes that im- 
portant as are the flavors developed by cooking in stimu- 
lating appetite and creating or arousing a keen relish for 
food, they are of but minor consequence as compared with 
the importance of freeing roast pig and similar foods from 
possible parasites such as Trichina, or tapeworms (p. 1 18). 
Writers on the physiology of cookery do not usually dwell 
sufficiently upon this aspect of the subject. They are 
accustomed, rather, to point to the greater digestibility of 
starches, meats, and fats when these are properly prepared 
for internal digestion by the external digestion (cookery) 
of the kitchen. They emphasize also the improved flavors 
developed, which arouse the appetite and stimulate the 
powers of digestion. These are unquestionably of great 
importance ; but probably far more important in the history 
of the race has been the fact that by fire food is largely 
purified from living parasites and other agents of infection. 



CHAPTER XIII 

ON THE PREVENTION AND INHIBITION OF INFECTION, DE- 
COMPOSITION AND DECAY. ASEPSIS AND ANTISEPSIS. 

§ I. — Asepsis, or the Prevention of Infection by Exclusion 

It has already been stated in a previous chapter that 
for the genesis of infectious disease two factors at least are 
necessary ; namely, first, an infectious substance, material 
or element, ordinarily a micro-organism; and, second, a 
susceptible subject. In other words, a state of infectious 
disease in an organism, whether plant or animal, depends 
upon an infectious element proceeding from the environ- 
ment and also upon a special condition of the organism 
such that it is capable of being successfully acted upon or 
interfered with by the infectious element or its products. 
Infectious disease in its transmission or distribution thus 
represents one phase of the eternal struggle for existence, 
or that interplay with the environment which is the funda- 
mental phenomenon of life (cf. p. 63). On the part of the 
organism attacked, it represents a phase in that continuous 
attempt at adjustment of internal to external relations 
which has been well defined as a leading characteristic of 
the life process (cf . p. 69). It will not do to assume that 
the cause of disease resides either in the infectious element 
alone or chiefly, or in the organism attacked alone or 
chiefly. The true cause of disease is to be found in the 
cooperation of both factors, namely, the infectious element 
and the susceptible organism. It cannot be denied, how- 
ever, that in the common, everyday use of the word " cause," 
it is the aggressor rather than the defendant which is prop- 

311 



312 THE PREVENTION AND INHIBITION OF INFECTION 

erly cited to appear ; and nothing is clearer than the fact 
that if the infectious element can be successfully excluded 
or warded off, the disease, which might otherwise appear 
as the result of its entrance or attack, can be avoided. 

Modern surgery is the best possible example of the 
beneficent results of this kind of procedure. Before any 
serious operation upon the internal portions of the organ- 
ism is, to-day, undertaken the parts upon which the incision 
is to be made are carefully cleaned, and even sterilized, 
with the sole object of excluding putrefactive or morbific 
germs. All knives and other instruments, all ligatures and 
similar appliances, are carefully freed by heat or by disin- 
fectants from possible septic, putrefactive or infectious 
elements, and the most extraordinary pains are taken to 
exclude as completely as possible all micro-organisms. 
Surgery of this kind is rightly called "aseptic," and 
although doubtless in many cases it is not absolutely suc- 
cessful in excluding every micro-organism, it is neverthe- 
less sufficiently so in the great majority of cases to insure 
the wonderful success which attends modern surgical 
operations. 

We have referred to aseptic surgery in an earlier chapter 
as " sanitary " surgery, and the justice of this appellation 
will be perceived when we point out that precisely the 
same kind of exclusion is sought for in the larger pro- 
cedures of the public health, as when, for example, a water 
supply is freed from the germs of infectious disease by 
exclusion. When pains are taken to see to it that no cases 
of infectious disease shall be allowed to infect a particular 
watershed, we are acting upon principles precisely similar 
to those invoked in a modern " aseptic " surgical operation, 
and there can be no doubt that the procedure is at least 
as reasonable and as desirable in the case of the water 
supply, which affects thousands, as in the case of a single 
patient undergoing a surgical operation. The life of the 
community may, in theory at least, and to a large extent 



ASEPSIS AND ANTISEPSIS 313 

in practice, be protected by the mere exclusion of patho- 
genic micro-organisms from water supplies, milk supplies 
and air supplies. 

§ 2. — Quarantine and Isolation 

It is the recognition of facts like these which have led 
even uncivilized peoples instinctively to the endeavor to 
ward off disease in a wholesale fashion by the exclusion 
of suspected persons, or by their detention at the frontier, 
of a particular country until time shall have demonstrated 
that they are or are not vehicles of infection. The word 
" quarantine " is in itself a witness to the custom of deten- 
tion, which in former times was sometimes forty days. 
Modern sanitary science has tended to show that quaran- 
tine, or the attempt of communities to protect themselves 
by the exclusion of human beings and merchandise which 
are possible vehicles of infectious disease, is only a rude 
and generally imperfect method of exclusion. There can 
be no question, however, as to the legitimacy of the 
fundamental principle involved. 

Of late years, and with the increasing evidence of the 
difficulty of securing freedom from infectious disease by 
exclusion, the practice of quarantine, at least in the old 
form and on the frontier, has fallen into comparative dis- 
repute. A modified form of quarantine, has, however, 
come into wider usage, namely, what is now known as 
"isolation." Isolation is essentially local or sporadic 
quarantine, in which the person or merchandise suspected 
of being a vehicle of disease is separated or isolated, 
wherever found, or in a convenient neighboring locality, 
from all other persons or articles of merchandise until 
the danger shall have passed, or the infectious materials 
have been destroyed. It is found practically that this 
method of local or sporadic quarantine in highly civilized 
countries is more perfect and successful, on the whole, 
than the wholesale or frontier quarantine; while it inter- 



314 THE PREVENTION AND INHIBITION OF INFECTION 

feres far less with the ordinary conduct of commercial 
life, and is therefore less subject to the usual tempta- 
tions to elude, evade or disobey quarantine regulations. 
Everything depends, however, in the prevention of in- 
fection by exclusion, precisely as is the case in sanitary 
surgery, upon the thoroughness with which the exclusion 
is carried out. Practically this means, in particular cases, 
that it depends upon the thoroughness with which the 
law is enforced and obeyed, and neither quarantine nor 
isolation can be successfully carried out in any country 
or in any community in which the police regulations are 
ignored or disobeyed. Hence it has come to pass that the 
less civilized nations still prefer to depend mainly upon 
frontier quarantine, where it is possible to keep up at least 
the form of prevention by exclusion ; whereas, if once the 
infectious materials should be introduced, it is realized 
that little or no dependence could be placed upon the 
thoroughness of local or sporadic isolation. On the other 
hand, the more highly civilized nations, which have confi- 
dence in their ability to quarantine locally, i.e. to isolate 
sporadic cases or even infected communities, lay compara- 
tively little stress upon frontier quarantine, well knowing 
how difficult and often impossible it is to make it thorough, 
preferring rather to depend upon such local quarantine by 
isolation of sporadic cases as may become necessary. 

There is still considerable difference of opinion as to the 
value of quarantine regulations. No one can doubt that in 
special cases, such as the arrival of ships in well-guarded 
harbors, it is still possible to effect important measures of 
protection by the exclusion of infection through quarantine 
control. This is particularly true of many cities and har- 
bors of the United States to which vessels may come after 
long periods at sea, bringing unmistakable evidence of infec- 
tious disease. Such vessels may well be, and often are, 
detained in quarantine in New York, or Boston, or San 
Francisco, with immense advantage to the public health. 



PREVENTION BY QUARANTINE AND ISOLATION 315 

But, on the other hand, such attempts at exclusion by 
quarantine regulations as have been frequently instituted 
along the sparsely inhabited frontiers of our Southern 
states, during periods of alarm because of yellow fever, 
are probably comparatively ineffective. 

§ 3. — Immunity y or the Prevention of Infection by Insus- 
ceptibility 

Nothing is clearer than the fact that the normal organ- 
ism possesses marked powers of resistance to the invasions 
of infectious disease, or that some individuals offer more 
resistance than others. Such variations in resistance may 
be described as variations in susceptibility, and total insus- 
ceptibility, or perfect resistance to infectious disease, is 
spoken of as immunity. The term " immunity" is, however, 
generally limited to specific immunity, i.e. immunity to a 
particular disease or diseases. Obviously, if general im- 
munity to infectious disease could be brought about, little 
attention would need to be paid either to the vehicles of 
infection or to the infectious elements themselves. Theo- 
retically and practically, the production of immunity in 
normal organisms, whether plant or animal, is the goal of 
sanitary science, so far at least as infectious diseases are 
concerned. At present, however, this goal is not even in 
sight, so that strenuous efforts must still be made, and prob- 
ably for a long time to come, to prevent infectious disease 
by the control or destruction of infectious elements in the 
environment, and by their exclusion from possibly suscep- 
tible individuals. 

Meantime, although the goal is not in sight, some steps 
toward it have been taken, at least in the case of certain 
diseases ; and although these have been dwelt upon already 
(p. 75), we may refer to them again at this point. The first 
progress consciously made in this direction was that in- 
volved in the process known as inoculation for small-pox, 



316 THE PREVENTION AND INHIBITION OF INFECTION 

and to a consideration of this process, with its natural 
corollaries, vaccination and serum therapy, we shall im- 
mediately return. At this point we may observe, in pass- 
ing, that insusceptibility appears to be in many cases very 
largely a matter of physiological vigor and robust living. 
There can be but little question that individuals of strong 
constitution, well fed, well housed, well trained physically, 
and free from corroding care, anxiety, trouble, overwork, 
want of sleep and similar depressing influences are 
materially strengthened in their powers of resistance to 
disease. These matters are of fundamental importance, 
therefore, to the public health, and the student of sanitary 
science must always bear in mind the significance for 
the public health of conditions favoring the most perfect 
operation of the animal organism. Overcrowding, over- 
work, overexcitement, underfeeding, undersleeping, under- 
exercise — in short, all conditions which tend to remove 
the organism from the normal in physical vigor — tend to 
the diminution of vital resistance and to the increase of 
susceptibility to disease. They are to be avoided as un- 
wholesome and unsanitary, while normal, happy, vigorous, 
physical life is to be encouraged as probably the most 
fundamental and far-reaching of all sanitary measures 
tending to promote the public health. 

§ 4. — Insusceptibility Artificially produced by Inoculation 

One of the earliest attempts, if not the earliest, to influ- 
ence directly the degree of susceptibility of the organism 
to an infectious disease was that of inoculation for small- 
pox. 1 This disease, like other well-known infectious dis- 
eases, such as the plague, appears to have been imported into 
Europe from Asia, where it had been known from remote 
antiquity. Early in the eighteenth century, and chiefly 
through letters of Lady Mary Wortley Montagu, it became 

1 This subject has already been discussed at length above (pp. 76-80). 



PREVENTION BY INSUSCEPTIBILITY 317 

known that a certain advantage to any individual liable to 
exposure to small-pox might be derived by direct inocula- 
tion with the virus of the disease intentionally introduced 
at a time when the subject was in good health, so that he 
should have the disease under the most favorable circum- 
stances, rather than possibly at some time when conditions 
might be less favorable. This method was known and 
practised in the East, or at least in Turkey, at this time; and 
chiefly through the letters from Constantinople of Lady 
Montagu it became known in, and was speedily introduced 
into, England and America. There is no reason to doubt 
that such inoculations tended in a marked degree to bring 
about individual insusceptibility and immunity ; and it is 
certain that under its influence the fatality of small-pox was 
lessened, while only a small percentage of those inoculated 
perished from the disease. 

The objections to inoculation, however, were great; for 
although usually those inoculated had the disease in a 
relatively mild form, occasionally the severest symptoms 
ensued, and disfiguration was not uncommon. Moreover, as 
the method was essentially one of cultivation of the disease, 
those inoculated became veritable centres of infection ; and 
it is said that, on the whole, the practice tended to spread 
the disease and, while benefiting individual cases, tended to 
increase the general mortality. It was gradually displaced 
after Jenner's discovery of vaccination by that far safer 
method of producing insusceptibility, and in 1840 an act 
of Parliament was passed rendering small-pox inoculation 
unlawful in England. 

The student of preventive medicine and immunity may 
find in the history of small-pox inoculation many valuable 
lessons, of which the most obvious and important is the fact 
that the normal healthy organism in its best estate is often 
able to resist the onslaughts of even very virulent diseases, 
directly and intentionally introduced into the body. Noth- 
ing could testify more clearly to the fundamental impor- 



318 THE PREVENTION AND INHIBITION OF INFECTION 

tance in sanitary science of personal hygiene, and the 
immense importance of keeping the body in the best pos- 
sible physiological condition. Herein, no doubt, lies the 
key to the explanation of the fact that in any epidemic, 
however widespread, a large percentage of persons escape 
the disease altogether, while another large percentage suf- 
fer from it but little. 

On the other hand, the history of inoculation teaches 
that even under conditions apparently the most favorable, 
a few who might be supposed to be naturally exempt, owing 
to abundant vitality, do, nevertheless, suffer in an almost 
inexplicable fashion. While, therefore, it is plainly the 
duty of the sanitarian to do everything in his power to pro- 
mote the practice of personal hygiene, it is no less his 
bounden duty to seek at the same time to remove the spe- 
cific causes of disease from the environment. The art of 
hygiene is, and probably always will be, twofold : on the 
one hand, the creation or promotion of personal insuscepti- 
bility; and, on the other, the control or abatement of the 
specific inciters of disease : this double duty consisting, 
on the one hand, of reenforcement of the organism, and 
on the other, of mastery of the environment. 

§ 5. — Insusceptibility Artificially produced by that Variety 
of Inoculation known as Vaccination 

By far the most interesting and important attempt to 
bring about insusceptibility to an infectious disease is vac- 
cination for small-pox 2 — an art now well known and fully 
tested all over the world. Introduced by Jenner at the 
end of the eighteenth century, and improved and ex- 
tended by his successors, vaccination is to-day the princi- 
pal weapon employed by the human race in its warfare 
with one of the most loathsome, and formerly one of the 

1 This subject has already been discussed briefly in another connection 
(p. 80). 



PREVENTION BY INSUSCEPTIBILITY 319 

most dreaded, of all infectious diseases. Its practice is 
justified not only by experience but also by experiment, 
for it has been conclusively and repeatedly proved by 
actual experiment that persons thoroughly vaccinated are 
for a longer or shorter time insusceptible to successful 
small-pox inoculation. (See e.g., Report, Boston Board 
of Health, for 1802.) 

The theory of vaccination depends simply upon the fact 
that comparative immunity appears to be produced in a 
vaccinated organism by causing it to undergo what is prob- 
ably a very mild form of small-pox, or, possibly, a cognate 
and much milder disease — namely, small-pox of the cow, 
or "cow-pox." Moreover, it is the usual custom to inocu- 
late persons whom it is desired to protect from small-pox 
with vaccine virus, as in the case of inoculation proper, 
when they are in good condition and well fitted to resist 
an attack of disease. 

Vaccination does not differ much in principle from the 
earlier art of inoculation ; and although it is not clear in 
either case how, precisely, a mild attack of the disease 
against which defence is sought, or of a related or modified 
form of the disease, such as cow-pox, confers immunity, 
various theories concerning this acquirement are extant, 
none of which can be said to be entirely satisfactory. 
The best is, perhaps, that of the reaction of the organism 
in the production of defensive antidotes to the specific 
virus, a matter which will be more fully explained in the 
next section. 

There is no doubt that comparative freedom of the most 
highly civilized peoples from small-pox is due in part to 
greater cleanliness and the improvement in sanitary condi- 
tions in general, which has been so marked a feature of the 
past century. Resting chiefly upon this thesis, a consider- 
able number of persons, known as anti-vaccinationists, deny 
altogether the efficiency of vaccination, and by dwelling 
upon the dangers of impure vaccine, and the possibility of 



320 THE PREVENTION AND INHIBITION OF INFECTION 

introducing the germs of other diseases into the organism, 
such persons object in to to to vaccination, and especially 
to vaccination made compulsory by statute. The great 
majority of careful students and dispassionate observers, 
however, while allowing a certain weight to these objec- 
tions, nevertheless firmly believe that the comparative 
scarcity of small-pox at the present time in vaccinated 
peoples, though probably due in part to improved sanitary 
conditions, is chiefly due to the almost universal practice 
of vaccination. 

In a disease so infectious, and even contagious, as small- 
pox is, it may even be doubted whether the extraordinary 
development of the possibilities of the spread of disease 
by travel and the like would not actually have caused an 
increase of small-pox, in spite of the general improvement 
in sanitary conditions, had it not been for the art of 
vaccination. There is reason, for example, to believe that 
typhoid fever has actually increased in many communities, 
owing to its more ready dissemination, in spite of the 
diminution which it must have undergone under general 
sanitary improvements. Typhus fever, on the other hand, 
has well-nigh disappeared, and disbelievers in the impor- 
tance and efficiency of vaccination claim to find in the 
history of this disease support for their views. 

§ 6. — Nineteenth Century Progress in the Art of Inocula- 
tion and Vaccination 

The applications of pure science usually follow close 
upon the heels of discovery, and long before the full estab- 
lishment of bacteriology steps had been taken to modify 
and control the action of bacteria in infectious disease. 

As early as 1880 Pasteur, reflecting upon the monumen- 
tal discoveries of Jenner, and upon the fact that small-pox 
must be supposed to be an infectious disease, perceived 
that a reasonable theory of vaccination, provided the germ 



PREVENTION OF ANTHRAX BY INOCULATION 32 1 

theory of disease were true, may be that somehow the 
germ of small-pox has been modified in the cow and ren- 
dered weak or " attenuated," so that when it is introduced 
into the human body it is no longer able to exhibit its 
former virulence. Filled with this idea, he accordingly 
undertook to produce a corresponding weakening or " atten- 
uation " in the germs of certain common diseases such as 
chicken cholera and anthrax. In this attempt, in 1880, he 
met with surprising success ; and it will be well worth 
while to note at this point an account of a public test of 
his work upon splenic fever vaccination which has been 
vividly portrayed by his son-in-law, M. Radot. 1 

§7. — A Public Demonstration by Pasteur of the Possi- 
bility of Protective Inoculation of Certain of the Lower 
Animals Against Anthrax or Splenic Fever 

"It was on February 28, 1881, that Pasteur communi- 
cated to the Academy of Sciences, in his own name 
and in those of his two fellow-workers, the exposition of 
his great discovery. Loud applause burst forth with 
patriotic joy and pride. And yet so marvellous were 
the results that some colleagues could not help saying, 
'There is a little romance in all this.' All this reminds 
one, in fact, of what the alchemist of Lesage did to the 
demons which annoyed him. He shut them up in little 
bottles, well corked, and so kept them imprisoned and inof- 
fensive. Pasteur shut up in glass bulbs a whole world of 
microbes, with all sorts of varieties which he cultivated at 
will. Virulences, attenuated or terrible, diseases, benign 
or deadly, he could offer all. 

" Hardly had the journals published the compte rendu 
of his communication, when the President of the Society of 
Agriculture in Melun, M. le Baron de la Rochette, came, 

1 " Louis Pasteur : His Life and Labors." By his Son-in-Law. From the 
French, by Lady Claud Hamilton. New York (Appleton), 1885. 
Y 



322 THE PREVENTION AND INHIBITION OF INFECTION 

in the name of the society, to invite Pasteur to make a 
public experiment of splenic fever vaccination. 

" Pasteur accepted. On April 28 a sort of convention 
was entered into between him and the society. The soci- 
ety agreed to place at the disposal of Pasteur and his 
two young assistants, Chamberland and Roux, sixty sheep. 
Ten of these sheep were not to receive any treatment; 
twenty-five were to be subjected to two vaccinal inocula- 
tions at intervals of from twelve to fifteen days, by two 
vaccines of unequal strength. Some days later these 
twenty-five sheep, as well as the twenty-five remaining 
ones, were to be inoculated with the virus of virulent 
splenic fever. A similar experiment was to be made upon 
ten cows. Six were to be vaccinated, four not vaccinated ; 
and the ten cows were afterward, on the same day as the 
fifty sheep, to receive inoculation from a very virulent virus. 

" Pasteur affirmed that the twenty-five sheep which had 
not been vaccinated would perish, while the twenty-five 
vaccinated ones would resist the very virulent virus ; that 
the six vaccinated cows would not take the disease, while 
the four which had not been vaccinated, even if they did 
not die, would at least be extremely ill. . . . 

"The experiments began on May 5, 1881, at four kilo- 
metres' distance from Melun, in a farm of the commune of 
Pouilly-le-Fort, belonging to a veterinary doctor, M. Ros- 
signol, Secretary-general of the Society of Melun. At 
the desire of the Society of Agriculture, a goat had been 
substituted for one of the twenty-five sheep of the first lot. 
On the 5th of May they inoculated, by means of the little 
syringe of Pravaz, — that which is used in all hypodermic 
injections, — twenty-four sheep, the goat and six cows with 
five drops of an attenuated splenic virus. . . 

" On May 3 1 very virulent inoculation was effected. 
Veterinary doctors, inquisitive people and agriculturists 
formed a crowd round this little flock. The thirty-one 
vaccinated subjects awaiting the terrible trial stood side by 



A DEMONSTRATION OF ANTHRAX VACCINATION 323 

side with the twenty-five sheep and the four cows, which 
awaited also their first turn of virulent inoculation. Upon 
the proposal of a veterinary doctor, who disguised his 
scepticism under the expressed desire to render the trials 
more comparative, they inoculated alternately a vaccinated 
and a non-vaccinated animal. A meeting was then arranged 
by Pasteur and all other persons present for Thursday, 
June 2, thus allowing an interval of forty-eight hours after 
the virulent inoculation. 

" More than two hundred persons met that day at Melun. 
The Prefect of Seine-et-Marne, M. Patinot, senators, gen- 
eral counsellors, journalists, a great number of doctors, of 
veterinary surgeons and farmers ; those who believed, and 
those who doubted, came, impatient for the result. On 
their arrival at the farm of Pouilly-le-Fort, they could not 
repress a shout of admiration. Out of the twenty-five 
sheep which had not been vaccinated, twenty-one were 
dead ; the goat was also dead ; two other sheep were 
dying, and the last, already smitten, was certain to die 
that very evening. The non-vaccinated cows had all 
voluminous swellings at the point of inoculation, behind 
the shoulder. The fever was intense, and they had no 
longer strength to eat. The vaccinated sheep were in full 
health and gayety. The vaccinated cows showed no tumor ; 
they had not even suffered an elevation of temperature, 
and they continued to eat quietly. 

" There was a burst of enthusiasm at these truly marvel- 
lous results. The veterinary surgeons especially, who had 
received with entire incredulity the anticipations recorded 
in the programme of the experiments, who in their conver- 
sations and in their journals had declared very loudly that 
it was difficult to believe in the possibility of preparing a 
vaccine capable of triumphing over such deadly diseases as 
fowl cholera and splenic fever, could not recover from their 
surprise. They examined the dead, they felt the living. . . . 

" Having suddenly become fervent apostles of the new 



324 THE PREVENTION AND INHIBITION OF INFECTION 

doctrine, the veterinary surgeons went about proclaiming 
everywhere what they had seen. One of those who had 
been the most sceptical carried his proselytizing zeal to 
such a point that he wished to inoculate himself. He did 
so with the two first vaccines, without other accident than 
a slight fever. It required all the efforts of his family to 
prevent him from inoculating himself with the most virulent 
virus. 

" An extraordinary movement was everywhere produced 
in favor of vaccination. A great number of agricultural 
societies wished to repeat the celebrated experiment of 
Pouilly-le-Fort. The breeders of cattle overwhelmed Pas- 
teur with applications for vaccine. Pasteur was obliged to 
start a small manufactory for the preparation of these vac- 
cines, in the Rue Vauquelin, a few paces from his labora- 
tory. At the end of the year 1881 he had already vac- 
cinated 33,946 animals. This number was composed of 
33,550 sheep, 1254 oxen, 142 horses. In 1882 the number 
of animals vaccinated amounted to 399,102, which included 
47,000 oxen and 2000 horses. In 1883, 100,000 animals 
were added to the total of 1882." 

These experiments drew universal attention to the sub- 
jects of immunity and susceptibility. It had been long 
recognized that there is such a thing as natural immunity as 
well as natural susceptibility, and the case of small-pox is 
familiar testimony to the fact that there is such a thing as 
acquired immunity. Pasteur's experiments, moreover, had 
abundantly demonstrated that immunity to anthrax could 
be artificially produced. These ideas fell in well with those 
concerning the toxins referred to in the third chapter 
(pp. 57, 59), for it was possible to see how, either by reducing 
the virulence of the toxins, or by accustoming the organism 
to them, gradually insusceptibility or virtual immunity might 
be produced. 

To discuss all aspects of this question, interesting though 
it would be, would carry us too far into the domain of bac- 



ANTITOXINS AS PROPHYLACTICS 325 

teriology and medicine. Suffice it to say that in one in- 
stance, at least, the studies upon this subject have already 
borne the richest fruit. Thanks to Behring, Roux and 
others, we are now able to produce at will not only the 
toxin of diphtheria, but also by simple procedures the an- 
tidote to this poison which is appropriately called its " anti- 
toxin." (Cf. p. 83.) 

§ 8. — Insusceptibility produced by Inoculation of Anti- 
toxins. Serum Therapy 

A logical extension of the arts of inoculation and vacci- 
nation now consists in the use of antitoxins to reenforce 
the natural insusceptibility of the organism, whether partial 
or complete. If, for example, as we have reason to believe, 
the specific diseases known as small-pox, plague, diphtheria, 
etc., are aroused by specific chemical excitants or poisons 
of the physiological mechanism, themselves produced by 
specific living excitants known as micro-organisms, it is 
reasonable to suppose that those animals or persons which 
are immune to these diseases must possess some special 
antidote capable of destroying the effects of the specific 
poisons or toxins which they generate and which are 
characteristic of them. By inductive reasoning of this 
sort Behring and Roux undertook to settle the question 
by gradually producing immunity to the toxin of diph- 
theria in horses, and then using the antitoxins presumably 
present in the blood of the immune horses as a curative or 
preventive weapon against diphtheria in man. We have 
already dwelt upon this subject in the preceding para- 
graph and elsewhere, and need not touch upon it further 
here. Suffice it to say, that it is now generally admitted 
on all sides that the antitoxin of diphtheria may be em- 
ployed successfully not only to reenforce the organism 
already suffering from the disease, but also as a prophy- 
lactic or means of prevention in others susceptible but 
not yet affected. The chain of reasoning and the experi- 



326 THE PREVENTION AND INHIBITION OF INFECTION 

mental work involved in this discovery constitute one of 
the most beautiful examples of patient scientific work in 
the whole history of experimental medicine and sanitary 
science. 

§ 9. — Antisepsis and the Prevention of Infection by 
Antiseptics 

Theoretically, it should be possible to inhibit or check 
the progress of any infectious disease within the organism 
by the use of substances capable of interfering with or 
inhibiting the growth and multiplication of the micro- 
organisms involved. In practice, however, to do this is 
far more difficult than might be expected, so that the pre- 
vention of infection by exclusion (asepsis), the prevention 
of infection by insusceptibility (immunity, natural or ac- 
quired), and external disinfection, or the destruction and 
removal of infection from the environment, — which lat- 
ter subject will be dealt with in the next chapter, — are 
infinitely more valuable methods of procedure in sanitary 
science. The reason for this is to be found partly in the 
difficulty of bringing to bear upon micro-organisms, scat- 
tered throughout masses of tissue or widely distributed in 
ducts or canals, agents capable of inhibiting or checking 
their activity, but chiefly in the fact that such agents are 
almost of necessity harmful to the organism which it is 
desired to benefit ; for it is a fact which should never be 
forgotten that micro-organisms capable of producing infec- 
tious disease, although removed from man and the higher 
animals by the whole length of the animal and vegetable 
kingdoms, are, nevertheless, composed of protoplasm, very 
similar in its chemical and physical properties to that which 
constitutes the basis of the higher forms ; so that, broadly 
speaking, and doubtless with many exceptions, we ought 
to expect a sensitiveness to inhibiting agents in the one 
class of organisms similar to that in the other. 

Agents capable of checking or inhibiting the growth of 



ANTISEPTICS VS. DISINFECTANTS 327 

micro-organisms, in the way above suggested, but without 
necessarily killing them, are known as " antiseptics," and 
the process of such inhibition or checking as "antisepsis." 
Obviously, all disinfectants or destroyers of infection are 
also antiseptics; but the reverse is not true, for antiseptics 
are not necessarily disinfectants. When sanitary surgery 
was first proposed, it was generally described as antiseptic 
surgery, and it was held, at least by some, that its object 
was to inhibit the activity of organisms already introduced 
into the organism through wounds. Very soon, however, 
it became clear that the process was most successful when 
made aseptic rather than antiseptic ; and while to-day the 
washings and dressings employed in surgery may, and 
probably sometimes do, act as antiseptics, the almost uni- 
versal endeavor is to secure asepsis, and not to run the 
risk of possibly imperfect antisepsis. We may safely 
grant, nevertheless, the possibility that the organism itself 
has antiseptic as well as disinfecting powers. 

§ 10. — Intestinal Antisepsis 

It has been proposed to introduce into the alimentary 
canal in certain diseases agents which, while capable of 
checking the progress or multiplication of the organisms 
of infectious disease there present, shall at the same time 
be harmless to the tissues lining the canal. This procedure 
is properly described as intestinal antisepsis ; but, while 
well worthy of investigation, must always be subject to the 
drawback of constant danger of damage to the living walls 
by any agents powerful enough to affect the perhaps far 
more hardy micro-organisms of disease. 

§ n. — The Control of Infection in Decomposition and 

Decay 

From the sanitary point of view, decomposition and 
decay must always and everywhere be regarded with sus- 



328 THE PREVENTION AND INHIBITION OF INFECTION 

picion, although they are normal processes in nature and 
often of high usefulness in the arts and industries of 
daily life. The reason for this is that they are usually 
effected by bacteria or other micro-organisms with which 
those of infections may, in theory at least, be readily asso- 
ciated. Moreover, the chemical products of decomposition 
and decay are sometimes objectionable or even dangerous, 
so that the race in its long experience has properly enough 
come to regard them with suspicion. Their prevention is 
obviously, therefore, often desirable, especially in the case 
of food products, and for this purpose antiseptics such as 
cold, dryness, weak acids, condensing and partial steriliza- 
tion are often practically useful. 

§ 12. — Sanitary Aspects of Refrigeration and Cold Storage 

Probably the best of all antiseptics is simple cold, and 
this is now applied to the prevention of decomposition and 
decay of food almost universally. Before the introduction 
of the use of ice, low temperatures were sought by house- 
wives by the keeping of foods in cold cellars, deep wells 
and the like ; but within the past fifty years the use of 
ice, at least in America, has become a commonplace. 
The household refrigerator is a simple antiseptic device 
for postponing the decomposition and decay of meats, 
milk, vegetables, fruit and the like. More elaborate re- 
frigerators, furnishing antisepsis in similar fashion, are 
provided in markets, groceries, milk-houses and like es- 
tablishments ; while in nearly all large cities there are 
nowadays huge structures known as " cold-storage " ware- 
houses, in which vast quantities of perishable materials 
are successfully subjected to the antiseptic action of cold. 
The equipment of the best types of cold-storage ware- 
houses is elaborate and costly, for they must be sub- 
stantially and carefully built, furnished with efficient 
ammonia machines, or similar appliances for the produc- 



REFRIGERATION AND ANTISEPSIS 329 

tion of cold, and capable of dry ventilation to prevent 
excessive moisture. Cold for antiseptic purposes and 
the preservation of food materials is also distributed, at 
least in Boston, through pipes to various markets, which 
maintain rooms chilled to a low temperature very much as 
steam is circulated in winter for the heating of apartments. 
The sanitary value of systems of this sort is probably great, 
for there is reason to believe, as has been pointed out in a 
previous chapter (p. 259), that the germs of infectious dis- 
ease do not as a rule long survive at very low temperatures. 

§ 13. — Sanitary Aspects of Desiccation, Drying, 
Evaporation 

A favorite and primitive method of food-preserving for 
meats, fruits and various other food materials has long 
been in use under the name of " drying," and that this 
method possesses important sanitary advantages seems 
highly probable, inasmuch as the micro-organisms of dis- 
ease do not readily withstand prolonged desiccation. If, 
for example, fruits, meats or vegetables which it is pro- 
posed to use for food happen to be in any way infected, 
but are afterwards thoroughly dried, there is reason to 
believe that such desiccation is highly unfavorable to the 
disease germs present. Their spores, however, in some 
cases probably survive, and it is possible that some of the 
vegetative germs even may not perish ; but yet the process 
of desiccation plainly possesses valuable sanitary advan- 
tages. These are perhaps less important than would other- 
wise be the case were it not for the fact that dried fruits are 
rarely eaten without having been first not only moistened 
but also thoroughly cooked or heated, so that the danger 
of the dissemination of disease by dried fruits such as 
dried beef, dried apricots, dried beans, etc., is probably 
small. 



330 THE PREVENTION AND INHIBITION OF INFECTION 

§ 14. — Sanitary Aspects of Smoking 

A similar line of reasoning applies to the use of smoked 
foods, such as fish, beef or hams. In this case the pro- 
cess of drying is accompanied by smoking, so that what- 
ever antiseptic or disinfecting effects may reside in smoke 
are added to those of desiccation. Smoked and dried 
herring, for example, are in many cases hung in vast 
quantities in comparatively close buildings, and subjected 
for a considerable period to the warmth and smoke of a 
slow fire; and inasmuch as there is reason to believe that 
smoke possesses important disinfecting properties due to 
the creosote or other materials which it contains, the pro- 
cess must be regarded as one of considerable sanitary 
significance. 

Furthermore, inasmuch as smoked foods are not in- 
frequently eaten without cookery of any kind, their 
treatment is of special interest to the sanitarian. In all 
probability, the processes to which smoked foods have 
been subjected, while not such as to produce complete 
disinfection, are nevertheless sufficient to destroy most of 
the germs of infectious disease. If, nevertheless, after 
having been smoked and dried, such foods are handled 
by unclean persons and then eaten raw, they constitute 
a source of danger similar to that which resides in all 
raw foods. 

§ 1 5. — Of Preserving 

The process known as preserving is one in which decom- 
position is arrested or prevented by the use of syrups or 
other substances of considerable density, which in one 
way or another furnish an unfavorable environment to the 
organisms of decomposition and decay. A similar state- 
ment may probably be made in this case as in the pre- 
ceding, namely, that if the food to be preserved be infected, 
most of the infectious organisms will probably be destroyed 



ANTISEPTIC PROCESSES IN THE HOUSEHOLD 331 

in the process, though some may survive ; and if later the 
food material of which they constitute a part be eaten 
without having been cooked, a certain amount of danger 
may ensue. The dangers in this case, also, are, however, 
probably small. 

§ 16. — Of Canning 

The art of canning when properly carried out consists in 
a total destruction of all micro-organisms present, or dis- 
infection, and this process therefore belongs properly in the 
following chapter. It sometimes happens, nevertheless, 
that canned foods are only imperfectly sterilized, and when 
this is the case, it is clear that such foods may be bearers 
not only of fermentation, decomposition and decay, but, in 
special instances, of infection as well. At the same time, 
inasmuch as it is likely that the germs of putrefaction and 
decay will have made the contents of such cans unattrac- 
tive or repulsive, there is probably very slight danger of 
infection from canned foods. In some cases, indeed, 
this may not be true, the germs remaining after partial 
sterilization being of a kind incapable of producing 
ordinary and obvious decomposition and decay. For 
example, sweet corn after imperfect sterilization in cans 
not infrequently sours more or less, owing to the presence 
of certain bacteria capable of producing lactic acid from 
the substances present, and in this case the souring may 
not have proceeded so far as to make the corn inedible. 
Under these circumstances, the possibility of the convey- 
ance of infectious materials must be allowed ; but, as has 
been stated, its likelihood is probably only slight. 

§ 17. — Of Pickling 

Another important method of securing disinfection and 
antisepsis is the art of pickling, or the preservation of 
foods in brines, vinegar, weak acids and the like. In this 



332 THE PREVENTION AND INHIBITION OF INFECTION 

case, while the antiseptics employed are sufficient to pre- 
vent decomposition and decay, it is unlikely that thorough 
sterilization or disinfection is always brought about, and 
the bare possibility of the distribution of disease through 
infected foods thus preserved must be kept in mind, al- 
though it is not probable that much disease, other than a 
few "sporadic " cases, actually is caused in this way. 

§ 1 8. — Sanitary Aspects of Pasteurizing 

A process now much used for food-preserving is that 
form of partial sterilization by heat known as pasteurizing. 
This is now much employed in the dairy industry in the 
pasteurizing of milk and of cream. It is of immense im- 
portance as a practical means of food-preserving, and from 
the standpoint of sanitary science, if carefully conducted, 
is also of great value. As carried out, for example, in the 
preservation of milk, the attempt is made to use a tempera- 
ture high enough to secure the destruction of disease-pro- 
ducing germs, yet not so high as to produce the well-known 
" cooked " taste. There is much evidence of the sanitary 
efficiency of this process, which is always to be highly 
commended in the milk supply industry, but it cannot be 
denied that unless the pasteurizing is carried on at a high 
enough temperature to destroy all disease germs, such milk 
may still be the vehicle of infectious disease. (Cf p. 287.) 

§ 19. — Of Condensing 

Condensed foods, such as condensed milk, are usually 
thickened by heat, but the temperature employed is often 
insufficient to secure in itself the complete destruction of 
all micro-organisms. The change in the physical condition 
involved in the thickening is of sanitary value, and the 
whole process is one of considerable sanitary importance. 
It is doubtful, however, whether, under certain circum- 
stances, all germs of disease are destroyed in " condens- 



ANTISEPTICS IN THE ARTS AND INDUSTRIES 333 

ing," and the possibility that condensed foods may serve 
as vehicles of disease should be borne in mind, although it 
must be admitted that these are most likely, as a rule, 
safe and wholesome in this particular. 

It has recently been proposed to condense milk and other 
food materials by cold instead of by heat. The purification 
of water by freezing has already been dwelt upon in a 
previous chapter (p. 252), and the effect of cold upon 
disease germs is undoubtedly, as a rule, highly prejudicial 
to them, so that this process, if it becomes practical, must 
be allowed to possess important sanitary advantages. At 
the same time the possibility of the survival of a small per- 
centage of disease germs cannot, in the present state of our 
knowledge, be disregarded. 



CHAPTER XIV 

ON THE DESTRUCTION OR REMOVAL OF INFECTION. 
DISINFECTION AND DISINFECTANTS 

§ I. — Definitions 

Disinfection is the term applied to any process by 
which the infectious properties of anything are removed 
or destroyed, and a disinfectant is any agent or factor by 
which this process may be brought about. Obviously, dis- 
infection may be either partial or complete, but the term 
is usually applied only when the process, whatever it may 
be, is completely effective. Disinfection differs from asep- 
sis in the fact that the presence of infection in the material 
to be disinfected is assumed, while in asepsis the endeavor 
is made to prevent or forestall infection. In other words, 
disinfection is in the nature of cure or correction of an 
infectious condition, while asepsis is an effort directed to 
the avoidance, and antisepsis to the inhibition or control, 
of infection. A little consideration will show that all dis- 
infectants are naturally antiseptics, while antiseptics may 
or may not be disinfectants. Similarly, it may in any 
particular case happen that a disinfectant when diluted, or 
allowed to work for a brief period only, may act as an 
antiseptic ; while an antiseptic, working for a long time or 
in unusual concentration, may become a disinfectant. As 
has been pointed out in the previous chapter, antisepsis is 
of value largely in food-preserving, to which process disin- 
fection may also be applied. On the other hand, disinfec- 
tion may often be too poisonous or drastic for application 
to food-preserving, and in general the term is usually 
applied to the purification of substances (clothing, houses, 

334 






DISINFECTANTS VS. ANTISEPTICS 335 

etc.) other than food from the germs of disease, and only 
rarely to the arts of food-preserving. 

§ 2. — Disinfection by Chemical Agencies 

Fire is from every point of view the most valuable and 
effective disinfectant. We have already pointed out in a 
previous chapter how the disinfection of food by cookery 
is perhaps the most valuable part of that process, and the 
experience of the race has taught that it is no less effec- 
tive in other directions. Infected houses, infected bedding, 
infected clothing, are readily disinfected by fire. Fire has 
always been, and probably will always continue to be, the 
simplest, the readiest, and the most effective of all disin- 
fectants. It has often been suggested that the great fire 
of London in 1666, following as it did hard after the 
plague, was probably a most important factor in the 
purification of the city and the control of that dread 
disease. 

The precise manner in which fire destroys infection is 
easy to understand. By the production of a temperature 
so high that no life can withstand it, and the destruction 
of organic matter, the germs of disease, whether animal or 
vegetable, are readily destroyed, and fire may perhaps be 
considered, by virtue of the chemical decomposition which 
it brings about, as essentially a chemical disinfectant. 

Next in readiness and efficiency after fire come the 
chemical poisons, such as corrosive sublimate (mercuric 
chloride), carbolic acid, strong mineral acids and alkalies, 
sulphurous acid, formic aldehyde and the like. These, 
by producing chemical decompositions upon or within the 
cells of the organized infectious elements, so alter the 
chemical composition of the latter as to destroy their vital 
activity. In some cases, owing to special protective condi- 
tions, or forms which the infectious elements assume, all of 
these poisons may become for a longer or shorter time more 



336 DISINFECTION 

or less ineffective — a state of affairs which is probably 
common under the action of various so-called disinfectants. 



§ 3. — Disinfection by Physical Agencies 

Closely analogous to the effects just described as due to 
fire and poisons are those which come from heat, a mod- 
erate degree of temperature being favorable to the con- 
tinued life of organized infectious elements, but higher 
temperatures being more and more prejudicial to them. 
In general, it may be stated that the boiling temperature 
of water destroys most ordinary infectious materials, doubt- 
less by causing chemical changes similar to those referred 
to in the previous section ; but, as has been shown in the 
previous chapter, it is often necessary to use a tempera- 
ture considerably higher in order to sterilize, for example, 
canned foods. Moreover, microbes have been found 
which, though probably not capable of producing disease, 
are nevertheless able to withstand continuous boiling for 
eight hours or more. The assumption in this case is that 
spores are present, and are specially resistant in regard 
to conductivity of heat, so that their interior does not, 
until after a very long time, rise in temperature to the 
death point. It is not certain, however, whether their 
resistance is due to the fact that they are good non-conduc- 
tors or to some special property which is not understood. 

Cold in general is less effective than heat as a disin- 
fectant, and perhaps scarcely has a place among disinfec- 
tants. Nevertheless the evidence referred to in the case 
of the purification of ice in freezing (p. 261) indicates that 
cold does in fact play a very considerable part, not only as 
an antiseptic, but also as a disinfectant. The experience 
of the race, moreover, points in the same direction. In 
the southern United States cold weather is rightly believed 
to diminish materially the dangers from yellow fever and 
similar diseases, and there is reason to believe that the 






BY HEAT, COLD, DRYNESS, LIGHT . 337 

infectious elements of this disease, as well as of Asiatic 
cholera, typhoid fever, and probably many other diseases, 
are largely destroyed by prolonged exposure to even a 
moderate degree of cold, i.e. by temperatures in the vicinity 
of the freezing-point of water. 

Another powerful agent of disinfection is dryness. Liv- 
ing things require not only a favorable temperature, but 
also considerable moisture ; and a high degree, or a long 
period, of dryness undoubtedly contributes to the destruc- 
tion of germ life. It is doubtful, however, whether dry- 
ness, as it occurs in periods of drought or in nature 
generally, is a perfect disinfectant. There is reason to 
believe that precisely as prolonged moderate heat is 
required in order to destroy infection, and precisely as 
prolonged low temperatures are necessary, so prolonged 
dryness is required unless it be brought about in the most 
thorough manner and by artificial means, and possibly not 
even then. 

One of the most interesting discoveries in bacteriology 
of recent years was that which showed the germicidal 
efficiency of light. It had been known for some time to 
botanists that insolation, or the exposure of living organs 
or organisms to the light, appeared to bring about a rela- 
tively rapid disintegration of their protoplasm. Much 
evidence pointing in this direction was collected during 
the various studies which were made upon the function 
of chlorophyl, one view in particular (that of Pringsheim) 
being known as the " screen " theory, in which it was sup- 
posed that the green pigment of leaves serves as a screen 
to protect the underlying protoplasm from the injurious 
rays of the sun. It is now well known that sunlight has 
a marked germicidal power, and is, therefore, an important 
disinfectant. It is probably for this reason, in part at least, 
that the human race has, by experience, found sunlight so 
desirable in human dwellings and so effective an aid to 
healthy living. 



338 DISINFECTION 

Much has been hoped for, by some, from electricity as 
a disinfectant ; but the experimental evidence thus far 
available does not seem to justify any great expectations 
in this direction. Infectious organisms are themselves so 
similar in their resistance to the human body, or the foods 
in or upon which they may be, that it does not at present 
seem likely that it will in the near future be possible to 
destroy such germs by electric currents, without, at the 
same time, destroying their hosts, or the media upon which 
they may reside. 

§ 4. — Disinfection by Mechanical Means 

The processes thus far described or referred to for the 
most part bring about disinfection by destruction of the 
infectious elements. The definitions given at the begin- 
ning of this chapter, however, imply the possibility, in 
some cases at least, of removal without destruction; and 
such processes are, in fact, conceivable and practicable. 

Such a separation or removal may, for example, take 
place mechanically in filtration. If a drinking water, for 
instance, can be made to pass through a material of which 
the pores are so fine as to be impassable by the infectious 
elements, while yet permeable by water, then, clearly, the 
former may be held back while the latter may pass on. 
Such a mechanical filtration is plainly one form of disin- 
fection. 

Another form of mechanical disinfection is that effected 
by gravity. It has been pointed out above that a polluted 
water brought to rest and stored may be purified, in part, 
by sedimentation. If the infectious elements are heavier 
than the liquid in which they float, they may be drawn 
down by gravity and deposited upon the mud at the bottom 
of a reservoir, lake or other body of quiet water ; and such 
sedimentation may either constitute or contribute to a 
genuine disinfection of a water supply. 



BY FILTRATION, GRAVITY, STARVATION, ETC 339 

§ 5 • — Disinfection by Biological Agencies 

If the infectious elements in any given case can be 
detained long enough in the absence of food, starvation 
must eventually ensue; and there is little doubt that in 
certain water supplies, and elsewhere, this condition con- 
stitutes, or may constitute, a genuine factor of disinfection. 
Perhaps it is not too much to say that starvation of the 
infectious elements is, broadly speaking, and next to fire, 
one of the best of all disinfectants. In regard to the cycli- 
cal changes to which infectious elements are subject, we 
have very little knowledge, but if old age may be con- 
ceived to be a characteristic of the lowest forms of life, 
— a question which is still under debate, — then this also 
may well constitute one of the agents of disinfection. 

Finally, we may have, acting together in cooperation, 
two or more of the agencies already mentioned, such, for 
example, as cold and dryness, light and heat, or poisons 
and starvation, these together constituting what are called 
"unfavorable environments." Contrary to the opinion 
which was held in the earlier periods of our acquaintance 
with micro-organisms, we are now able to perceive that 
each of these must be carefully adjusted to its environment, 
if it is to survive long; and perhaps no factors are more 
effective in the control of infection than the unfavorable 
environments of infinite variety to which such elements 
must be subjected. It is probably here that we find the 
explanation of the sanitary improvement observed in the 
storage of water, ice, etc. (cf. pp. 237, 249, 261). 



§ 6. — The Problem of Disposal of the Dead 

The question of sanitary disposal of the dead concerns 
us chiefly so far as relates to its bearing upon the spread 
of infectious disease, and it is only this aspect of the 
subject which will be touched upon here. It has been 



340 DISINFECTION 

repeatedly stated in earlier chapters that the bacterial 
population of the living earth is a scavenging population, 
which removes from the surface of the earth the organic 
matters falling upon it, and converts them into inorganic 
matters. The same thing is true of organic matters placed 
at a moderate depth in the crust of the earth. The sub- 
soil is less abundantly supplied with bacteria than the loamy 
layers of vegetable mould at or near the surface, but yet 
contains a sufficient number of them to bring about the 
somewhat less rapid decomposition of organic matters. 
Human bodies, therefore, buried in the earth, and the 
wooden boxes in which they are usually interred, are in 
time gradually mineralized, and, in favorable cases, nearly 
all traces of organic matter disappear. The use of metal 
caskets, embalming fluids (which are usually powerful 
disinfectants, or at least strong antiseptics), simply delay 
the process. If any infectious germs be present in or 
about the dead body, these are obviously harmless so long 
as they remain in the earth. The only question is, whether 
they may survive to be brought to the surface by earth- 
worms or other agencies; for if so, after having been 
pulverized, they may be distributed by the wind. This 
subject has been carefully investigated by various ob- 
servers, and there seems little reason to believe that 
infectious materials may readily be spread abroad from 
infected bodies buried in the earth. Moreover, there are 
good grounds for believing that owing to unfavorable 
environment, old age, or other disinfecting agencies, the 
infectious germs, if present, will generally not very long sur- 
vive ; so that we appear to be safe in concluding that from 
the sanitary point of view there is little to be feared from 
disposal of the dead by interment. 

Much has been written and claimed in regard to nox- 
ious vapors arising from graveyards and in regard to 
graveyards, especially when crowded, as sources of disease. 
These ideas, however, are not founded upon good evidence, 



THE PROBLEM OF DISPOSAL OF THE DEAD, 341 

and there is reason to believe that whatever diseases 
may have appeared in the neighborhood of graveyards, 
have had their origin elsewhere. 

§ 7. — Interment vs. Cremation 

If what has just been said is true, no very powerful argu- 
ment can be found in sanitary science for cremation as 
opposed to interment. Nevertheless, the author firmly 
believes in cremation as the better process for the disposal 
of the dead, but simply for the following reasons : first, 
because it is speedy rather than tardy, and by cleanly com- 
bustion rather than foul decay, — fire accomplishing in a few 
hours a decomposition and a mineralization which require 
years at the hands of the bacteria ; second, because of the 
smaller space required for the keeping of the ashes and 
the possibility of restricting the immense areas likely in the 
future to be required for cemeteries ; and third, because of 
the removal of all ground for debate as to the possibility of 
damage from noxious vapors or the origin of disease from 
graveyards. 

§ 8. — Special Disinfectants 

The art of disinfection is a difficult and delicate one if it 
is desired that the 1 disinfection in any possible case shall be 
absolutely thorough and complete. There is a large litera- 
ture upon this subject to which many references might be 
given ; but the following brief statements must suffice for 
a work devoted to the principles, rather than the practice, 
of sanitary science. 

One of the best and most convenient disinfectants, as has 
already been pointed out, is fire. Almost every house, at 
least in temperate latitudes, is provided with a possible dis- 
infecting apparatus in the shape of a stove, a fireplace or 
a furnace. The only partial exception that has come to the 
author's notice is the case of those houses in the interior 
of the United States in which natural gas is used for cook- 



342 DISINFECTION 

ing and heating. As this produces no ashes, it is said by- 
housekeepers in these neighborhoods to be a matter of 
some inconvenience to get rid of dust and wastes which 
in other parts of the world are usually thrown into the 
stove or the furnace and burned. 

Boiling water is an excellent disinfectant, which is usually 
available in almost every household. If soap be added to 
it, the chemical effect of the alkali is added to the physical 
effect of the heat, and better disinfection is brought about. 
The scrubbing of a floor with hot soapsuds is an admirable 
though primitive way of removing infection, and one of the 
best mechanical disinfectants is probably washing followed 
by thorough rubbing, which shall dislodge infectious mate- 
rials from the surface of the body, from clothing, walls, etc. 

The first of the chemical disinfectants to receive general 
attention was carbolic acid, which was introduced shortly after 
Pasteur's investigations referred to in the second chapter. 
This, though still held in high popular esteem, has been 
largely superseded by more effective germicides, among 
which we may mention corrosive sublimate and formic 
aldehyde (formalin). A great variety of special disinfec- 
tants is now upon the market; but this is not the place 
to consider their merits. One of the simplest and most 
useful of household disinfectants is the milk of lime, 
freshly made; and even when stale, lime-water is still a 
valuable disinfectant. 

§ 9. — GermicidaUEfficiency Tests 

In order to test the efficiency of any particular germicides, 
careful precautions must be taken. It is not enough to mix 
a measured portion of the germicide with a liquid containing 
bacteria, and then to observe whether or not a portion of the 
mixture will grow upon the ordinary bacterial soils, such as 
gelatine or agar, for in this case some of the germicide may 
have been carried over, and though dilute, may nevertheless 



SPECIAL DISINFECTANTS AND GERMICIDES 343 

continue to act over a long period. Various methods have 
been devised in order to avoid this fundamental difficulty ; 
but none of them are wholly satisfactory. A discussion of 
the question may be found in a paper by the author entitled 
" Germicidal Efficiency Test of a Disinfectant to be used 
in Railway Sanitation." Technology Quarterly, Vol. IV, 
No. 2. Boston, 1893. 

§ 10. — Present State of the Art of Disinfection 

Under state and municipal control the art of disinfection 
has now reached a considerable degree of efficiency. It is 
practicable by means of steam, or the vapors of particular 
substances such as sulphurous acid or formalin, to disinfect 
with some success buildings, ships, apartments, furniture 
and the like, but much still needs to be done upon this 
subject. Those who desire to pursue this part of the sub- 
ject are referred to Dr. C. V. Chapin's valuable work on 
" Municipal Sanitation in the United States." Providence, 
R.I., 1901. 

§ 11. — Intestinal Disinfection 

An ingenious procedure has been suggested in the case 
of certain infectious diseases, especially such as affect the 
intestines or other portions of the alimentary canal, namely, 
that it may be possible to disinfect the alimentary canal or 
other special portions of the body. In the case of typhoid 
fever, for example, it is suggested that substances might 
be swallowed which, while passing through the mouth and 
stomach, should be harmless, but on reaching the small 
intestine should become decomposed or converted into 
antiseptics or even into disinfectants powerful enough to 
destroy the micro-organisms of disease yet not powerful 
enough to damage the general organism. In certain cases 
of cystitis, believed to be due to the typhoid bacillus, it is be- 
lieved that substances may even now be introduced into the 
body which on reaching the bladder actually become effec- 



344 DISINFECTION 

tive disinfectants capable of destroying the germs of the 
disease. If the hopes raised by these suggestions prove to 
be justified, internal disinfection of special portions of the 
body will then have realized Professor Tyndall's fancy of 
the cunningly devised torpedo which when swallowed shall 
find its way to the diseased point of the organism and by 
exploding there do effective work in destroying the germs 
of disease. 






PART III 

APPENDIX 






APPENDIX 

ON SOME POPULAR BELIEFS AS TO CERTAIN SPE- 
CIAL AND PECULIAR CAUSES OF DISEASES 

" Depend upon it, in all long-established practices or spiritual formu- 
las there has been some living truth." — J. A. Froude. 

§ i. — Vagaries of Sanitary Pseudo-Science 

There is perhaps no subject in which popular errors are more 
prevalent than in sanitary "science." This is doubtless due to 
the fact that while disease has long been only too familiar and 
well known, any accurate knowledge of the nature and causes of 
disease is comparatively modern. With the advent of rational 
conceptions of the nature and cause of diseases, more or less 
misunderstanding and misconception of the application of these 
notions was perhaps inevitable. It seems worth while, therefore, 
to dwell briefly upon some of the more widespread of the falla- 
cious notions or half-truths of sanitary science, and to define 
explicitly the present attitude of the best opinion of the time in 
regard to certain subjects relating to the public health, commonly 
misunderstood or misinterpreted. 

§ 2. — The Belief in Dangers from Sewer Gas 

It is commonly believed that much sickness is directly caused 
by the emanations of gases from sewers, drains, cesspools or 
other receptacles for sewage and similar foul or decomposing sub- 
stances. This belief even goes so far popularly, and sometimes 
professionally, as to serve as the all-sufficient explanation for the 
occurrence of certain specific diseases, such as typhoid fever, 
dysentery, diphtheria and scarlet fever. 

347 



348 APPENDIX 

Closely examined, the belief in the efficiency of sewer gas 
as the cause, not only of general, but also of specific, disease 
appears to rest upon the idea that in some way or other 
poisonous gases, after having been formed in sewers, cesspools 
and the like by active decomposition of the foul substances 
therein, escape into the air, and being inhaled, either by virtue 
of their chemical character or by means of micro-organisms, for 
which they are a vehicle, produce insidious general poisoning or 
specific disease. It is very seldom, however, that the sewer-gas 
theory of disease is thus explicitly and clearly defined. More 
often it takes the form of the simple statement or belief that 
typhoid fever, dysentery, diphtheria or malaria, are directly pro- 
duced by broken drains ; and it is this form chiefly of the theory 
or belief which requires to be corrected. Sometimes the sewer- 
gas theory takes a more general form, vaguely hinting at obscure 
but powerful influences, as, e.g. in the following : " Now here is a 
removable cause of death. These gases, which so many thousands 
of persons are daily inhaling, do not, it is true, in their diluted 
condition, suddenly extinguish life. ... In their diluted state 
as they rise from so many cesspools and taint the atmosphere of 
so many houses they form a climate congenial for the multiplication 
of epidemic disorders, and operate beyond all known influences 
of this class in impairing the chances of life." (Simon, 1849.) 

The facts with regard to sewer gas, and the part which it plays 
in the causing of disease, appear at present to be as follows : 
In the first place, there is reason to believe that the dangers of 
sewer gas have been very much exaggerated. There is no doubt, 
of course, that sewage is a decomposing liquid, and that it may, 
and often does, contain the germs of specific diseases. But, on 
the other hand, the facts that workmen frequently spend much of 
their time in sewers with impunity, or work upon or about sewage 
in sewage-purification works or on sewage farms, seem to show 
that experience does not confirm the idea that the gases emanat- 
ing from sewage are always or necessarily dangerous. Further- 
more, careful chemical and bacteriological examinations of the 
air of sewers have shown, not only that dangerous gases cannot 
ordinarily be detected in such air, but even that sewer air is sin- 
gularly free from micro-organisms. A little reflection will show 






DANGER FROM SEWER GAS 349 

that these results might have been expected, for decomposition 
of sewage in the sewers is seldom very advanced or extensive ; 
while the air of sewers, being very quiet, ought to contain few 
bacteria. 

If, now, we turn to stagnant sewage, such as might result from 
broken drains, or such as commonly exists in cesspools, we may 
reasonably expect to find more dangerous and more concentrated 
gases. We may even suppose that these are poisonous, and that, 
finding their way into human habitations, they are capable of 
producing sickness. There is no reason to doubt that some cases 
of sickness have in fact thus arisen, and to this extent the belief 
in sewer gas as a cause of disease is probably sound. In such 
cases, however, the sickness may be expected to take either the 
form of sudden, sharp attacks, suggestive of poisoning, or else 
the form of malaise and a general lowering of the vital resistance, 
lassitude, weakness, etc. 

While thus freely granting the possible efficiency of sewer gas 
as a general poison and depressant, we are very far from allowing 
the remaining and more popular form of the belief in sewer gas, 
namely, that it is capable of directly producing specific diseases, 
such as typhoid fever and diphtheria, which absolutely require 
for their genesis the introduction into the body of their own 
peculiar germs. The popular belief must presuppose that sewer 
gas is somehow a vehicle for these particular germs, which are 
lifted by it from the sewers or cesspools, and conveyed with it 
into the alimentary or respiratory passages of the victim ; and 
it is this part of the theory which cannot readily be allowed by 
the student of sanitary science. (See quotation from Budd, be- 
yond, pp. 35 4-35 5.) The reader who wishes to pursue this sub- 
ject further is referred to the valuable treatise by H. A. Roechling, 
C.E., entitled " Sewer Gas and its Influence upon Health." Lon- 
don, Biggs and Co., 1898. 

§ 3. — The Belief in Danger fro?n Well Waters 

One of the most widespread of the popular sanitary beliefs of 
the time is that which regards with suspicion the waters of ordinary 
domestic wells. This is a comparatively novel point of view, for 



350 APPENDIX 

until within the memory of the present generation the domestic 
well was regarded as one of the most valuable adjuncts of all 
well-regulated houses. Even to-day most country people, when 
informed by pseudo-sanitarians that grave danger resides in the 
family well, from which perhaps several generations of their ances- 
tors have drunk with satisfaction and benefit, refuse to entertain 
the idea that serious danger can possibly exist in anything so 
thoroughly tested and so long highly regarded. 

There is probably some truth in both points of view. The caus- 
ation of cholera by the Broad Street well, referred to in a previous 
chapter (p. 170), and other equally undoubted examples of infec- 
tion from polluted wells, have led to the generalization that serious 
danger often lurks in well waters. On the other hand, there are 
in existence innumerable examples of domestic wells which have 
faithfully ministered to the wants of families through long and 
successive generations; so that while it is true that well waters 
are sometimes dangerous, it is no less true that they are by no 
means always dangerous. 

The popular confusion of the matter has probably arisen through 
inaccurate reasoning as to the ways in which wells may become 
infected. The common form of theory in this particular — at 
least in the United States — is essentially as follows : Inasmuch 
as ground water readily moves through the earth, and inasmuch, 
further, as polluting materials are often deposited upon or within 
the earth, these may be borne by the underground water, which 
feeds the well, from a place of deposit upon or within the earth 
into the well itself. The picture which may readily be drawn of 
such contamination, or, as it is generally called, "leaching," through 
the earth, is simple ; and many more or less popular works upon 
hygiene have now for some years given illustrations showing the 
possible route taken by infectious materials, either from the surface 
of the earth, as, for example, from heaps of night soil or other ex- 
creta carelessly deposited there, or more often from leaky cesspools 
and the like, which may readily be so disposed in pictures, or in 
fact, as to appear to furnish pabulum for wells in the neighborhood. 

On the other hand, comparatively little is said in such cases 
about the dangers of infection from the top of the well. In the 
opinion of the author, however, it is precisely this source of infec- 



DANGER FROM WELL WATERS 351 

tion which is most to be dreaded, and, as a rule, is most effective ; 
for any one who reflects upon the filtering powers of the earth 
must readily perceive how unlikely it is that disease germs shall 
be able to survive in, and pass even a few feet through soil beyond, 
a leaky cesspool ; and that filtration and purification do, in fact, 
occur in ordinary domestic wells located in apparently dangerous 
proximity to barnyards and privies, is well shown by the chemical 
and bacterial composition of the waters collected from them. 

Excepting those cases in which cracks or fissures in the earth 
allow direct communication between polluting sources and wells 
of drinking water, the author is strongly of the opinion that in 
most cases in which infection exists in wells, the polluting mate- 
rial has found its way in from the top. Some examples of this 
kind have been given in a previous chapter, one of the most 
famous being the celebrated Caterham case (p. 191), in which 
the infection of a well in the chalk, by a workman who had 
gone in by the top, led to an alarming epidemic among persons 
supplied with the well water. 

When one reflects on the carelessness with which wells used 
as sources of drinking water are exposed to the access of filth 
from the top, such wells often being only loosely covered by 
planks, between which grasshoppers, toads or leaves frequently 
make their way, it is easy to see that from the boots of work- 
men, or from children playing on the planks, or from poultry 
walking about and carrying infection on their feet, pollution may 
readily take place. The author on one occasion noticed, for 
example, the following state of affairs. On a farm in an inland 
Massachusetts town were people sick with typhoid fever. The 
privy was freely open beneath and behind, and fowls were walk- 
ing about under it. The same fowls a little later were seen 
moving aimlessly and repeatedly about upon the old and worn 
pieces of planking which loosely covered the domestic well top. 
The well was provided with a pump, and in the water drawn by 
the pump milk cans were washed and rinsed before receiving milk 
to be shipped for the Boston market. There was reason at the 
time to suspect that certain cases of typhoid fever in a part of 
the distant city among the users of this milk had been caused by 
milk from this farm. Whether this was the case or not, the local 



352 APPENDIX 

conditions were certainly such as to allow ready pollution of the 
well water. 

The truth in regard to the dangers of well waters appears to be, that 
if the wells are thoroughly protected at the top from the entrance 
of filth, they are, as a rule, from the disease-producing point of 
view, unimpeachable, being perhaps indeed polluted with purified 
sewage, but not actually infected with the germs of disease. Such 
water should be regarded with suspicion and carefully avoided ; 
but yet, in the majority of cases, the water which they yield can- 
not reasonably be regarded as a probable vehicle of disease. 

"And I would add that certain observations which I made 
recently in a fever-stricken village . . . have induced me to 
think that of the two recognized foci for infection [in typhoid 
fever], the bespattered privy and the contaminated well, the 
former may be the one which is more commonly at work." — 
Professor George Rolleston, M.D., F.R.S.. TJie Lancet, March 
6, 1869. 

§ 4. — The Belief in Dangers from Broken Drains 

Another popular belief which requires careful examination is 
that of the efficacy of broken drains as causes of disease. From 
what has been said under the first section of this chapter in regard 
to sewer gas, the reader will surmise that the author attaches but 
little importance to sewers as direct sources of infectious disease. 
A broken drain may, and undoubtedly often does, yield more or 
less of objectionable and sometimes poisonous gases, but in the 
present state of our knowledge of the aetiology of disease it is very 
difficult, if not almost impossible, to understand how the accumu- 
lation of sewage in a cellar, or leakages of sewage from broken 
drains, or the escape of gases from such drains, can possibly 
provoke infectious disease. 

The belief in question has doubtless arisen, naturally enough, 
from a certain number of cases of coincidence between serious 
illness in the house and serious breaks in house drains. A well- 
known case of this kind occurred in Boston. The children of a 
family sickened and died from diphtheria ; and inasmuch as on 
examination broken drains were discovered in the basement, the 
conclusion was immediately drawn that the drains were the cause 



DANGER FROM BROKEN DRAINS 353 

of the disease. In many houses, however, broken drains occur, 
and even temporary accumulations of sewage matters, without any 
unfavorable consequences making their appearance. In the pres- 
ent state of sanitary science it is far more reasonable to suppose 
that the diphtheria was brought into the house by milk or other 
uncooked foods, or by a servant suffering from a mild form of the 
disease, or in some other unsuspected way, than to attribute it 
to the occult influence of broken drains. Here, again, the gases 
arising from leaks and breaks may have a toxic effect, and thus 
lower vital resistance and increase susceptibility. To this extent, 
and probably to this extent only, broken drains are " sources " of 
disease. 

§ 5. — The Belief in Bad Smells as Causes of Disease 

There can be no doubt that evil odors may produce temporary 
sickness. The inhabitants of Millbury, in the suit of the latter 
town against the city of Worcester, Mass., testified that they had 
been sickened by the smells arising from the polluted Blackstone 
River ; and the smell arising from tidal flats, covered at high tide 
by sewage-polluted waters and laid bare at low tide, may certainly 
be nauseous. On the other hand, there is no evidence whatever 
that typhoid fever or other infectious diseases can be directly 
caused in this way, so that while bad smells may be regarded as 
significant of putrefaction, decay, or even disease, and therefore 
useful warnings of trouble, they cannot in the present state of our 
knowledge be regarded as true sources of infectious disease. If, 
however, the vital resistance be lowered by such smells, they may 
favor, even if they cannot cause, disease. But it does not follow 
that bad smells do necessarily, though they certainly may, lower 
the vital resistance, at least so far as this can be measured by the 
death-rate. Thackrah, the founder of industrial hygiene, in his 
famous work, published in 1831, makes the following statement : — 

" The atmosphere of the slaughter-house, though sufficiently disgusting to 
the nose, does not appear to be at all injurious to health. The mere odors of 
animal substances, whether fresh or putrid, are not apparently hurtful; indeed, 
they seem to be often decidedly useful." 

One of the most famous stinks that has been recorded — if not 
the most famous — was that which arose from the Thames, in 



354 APPENDIX 

London, in 1858 and 1859. Nevertheless, as has been insisted 
by Dr. Budd, no very serious results followed. 

" The need of some radical modification in the view commonly taken of the 
relation which subsists between typhoid fever and sewage was placed in a very 
striking light by the state of the public health in London, during the hot 
months of 1858 and 1859, when the Thames stank so badly. 

" The late Dr. McWilliam pointed out at the time, in fitting and emphatic 
terms, the utter inconsistency of the facts with the received notions on the 
subject. Never before had Nature laid down the data for the solution of a 
problem of this kind in terms so large, or wrought them out to so decisive an 
issue. As the lesson then taught us seems to be already well-nigh forgotten, 
I may, perhaps, be allowed to recall some of its most salient points. 

" The occasion, indeed, as already hinted, was no common one. An extreme 
case, a gigantic scale in the phenomena, and perfect accuracy in the registra- 
tion of the results — three of the best of all the guarantees against fallacy — 
were combined to make the induction sure. For the first time in the history of 
man, the sewage of nearly three millions of people had been brought to seethe 
and ferment under a burning sun, in one vast open cloaca lying in their 
midst. 

" The result we all know. Stench so foul, we may well believe, had never 
before ascended to pollute this lower air. Never before, at least, had a stink 
risen to the height of an historic event. Even ancient fable failed to furnish 
figures adequate to convey a conception of its thrice-Augean foulness. For 
many weeks the atmosphere of Parliamentary committee-rooms was only ren- 
dered barely tolerable by the suspension before every window of blinds satu- 
rated with chloride of lime, and by the lavish use of this and other disinfectants. 
More than once, in spite of similar precautions, the law courts were suddenly 
broken up by an insupportable invasion of the noxious vapor. The river 
steamers lost their accustomed traffic, and travellers pressed for time often 
made a circuit of many miles rather than cross one of the city bridges. 

" For months together, the topic almost monopolized the public prints. 
Day after day, week after week, the Times teemed with letters filled with com- 
plaint, prophetic of calamity, or suggesting remedies. Here and there, a more 
than commonly passionate appeal showed how intensely the evil was felt by 
those who were condemned to dwell on the Stygian banks. At home and 
abroad, the state of the chief river was felt to be a national reproach. ' India 
is in revolt, and the Thames stinks,' were the two great facts coupled together 
by a distinguished foreign writer, to mark the climax of a national humiliation. 
But more significant still of the magnitude of the nuisance was the fact that 
five millions [of pounds] of money were cheerfully voted by a heavily taxed com- 
munity to provide the means for its abatement. With the popular views as to 
the connection between epidemic disease and putrescent gases, this state of 
things naturally gave rise to the worst forebodings. 

" Members of Parliament and noble lords, dabblers in sanitary science, vied 



AN HISTORIC STINK 



355 



with professional sanitarians in predicting pestilence. If London should hap- 
pily be spared the cholera, decimation by fever was, at least, a certainty. The 
occurrence of a case of malignant cholera in the person of a Thames waterman 
early in the summer was more than once cited to give point to these warn- 
ings, and as foreshadowing what was to come. Meanwhile, the hot weather 
passed away; the returns of sickness and mortality were made up, and, strange 
to relate, the result showed, not only a death-rate below the average, but, as the 
leading peculiarity of the season, a remarkable diminution in the prevalence of 
fever, diarrhoea, and the other forms of disease commonly ascribed to putrid 
emanations. 

"After describing in scientific and forcible terms the unprecedented state 
of the river, Dr. Letheby adds : ' With all this condition of the Thames, how- 
ever, the health of the metropolis has been remarkably good. In the corre- 
sponding period of last year {i.e. of the year 1857), the cases of fever, diarrhoea, 
and dysentery, attended in the city by the medical officers of the unions, 
amounted to 293 of the former, and 181 of the latter; but during the past 
quarter (i.e. the quarter of intolerable stench), they were only 202 of the 
former, and 93 of the latter ! ' 

" The testimony of Dr. McWilliam, as medical supervisor of the waterguard 
and waterside custom-house officers, is still more to the point. The former, 
to the number of more than eight hundred, ' may be said to live on the river, 
or in the docks, in ships, or in open boats; and the latter, numbering upward 
of five hundred, are employed during the day in the docks, or at the various 
wharves of the bonded warehouses on each side of the river.' After stating 
that the amount of general sickness among these men was below the average 
of the three preceding years, and considerably below that of the forms of dis- 
ease (including diarrhoea, choleraic diarrhoea, dysentery, etc.), which, in this 
country, noxious exhalations are commonly supposed to originate, we find the 
additions during the four hot months of the year from this class of complaints 
26.3 below the average of the corresponding period of the three previous 
years, and 73 per cent less than those of 1857. In another passage this dis- 
tinguished physician says : * It is nowhere sustained by evidence that the 
stench from the river and docks, however noisome, was in any way productive 
of disease. On the contrary, there was less disease of that form to which foul 
emanations are supposed to give rise than usual. 

" Before these inexorable figures the illusions of half a century vanish in a 
moment." — William Budd, Typhoid Fever, its Nature, Mode of Spreading 
and Prevention, pp. 148-151. London, 1873. 

Dr. Ord reported to the Privy Council in 1859 that in 1858 (the 
year of the worst stench) steamboat men on the Thames suffered 
severely from languor, headache, sore throat, nausea, giddiness, 
mental confusion, etc. (in other words from symptoms of poisoning). 
In 1859 the river was much better, and very few such symptoms 
occurred : " The greater weekly mortality has not coincided with 



356 APPENDIX 

the greater development of the stench, our most ready measure of 
the foulness of the stream. ... In both years the presence of 
sulphuretted hydrogen in the river atmosphere was shown by the 
rapid blackening of paper soaked in solutions of lead, and by the 
discoloration of the paint of vessels." — Second Report, Medical 
Officer of the Privy Council ', for 1859, p. 55. London, i860. 

§ 6. — Is Consumption Inherited! 

The discovery by Koch, in 1882, that tuberculosis is accompa- 
nied, and apparently originated, by a specific bacillus, has caused 
the popular belief that consumption is hereditary to be seriously 
questioned. The results of numerous experiments made by com- 
petent observers have tended to show that the germs of the disease 
are not often conveyed directly from parent to offspring, while the 
observations of pathologists have, as a rule, tended to indicate 
that new-born children of consumptive parents are free from all 
signs of the disease. On the other hand, no belief probably is 
more firmly rooted in the human race than that " consumption 
runs in families," and is peculiarly an hereditary disease. How,. 
it may well be asked, can these opposing results of experience and 
experiment be harmonized ? The answer is simple. If we assume, 
in accordance with the results of experiment, that the germs them- 
selves are not ordinarily inherited, we are not thereby prevented 
from supposing that those special constitutional qualities which 
allowed the disease to prevail in one generation are inherited, so 
that, while the germs themselves may not be carried on directly 
from generation to generation, a soil suitable for their develop- 
ment and multiplication is nevertheless inherited, and only requires 
to be sown with the germs in question in order to give rise to the 
disease. In other words, while the disease itself and its agents 
are ordinarily not inherited, a predisposition to the disease, a ten- 
dency, a weakness, or a condition favorable to the disease, may 
be thus derived. 

For example, a child of consumptive parentage may conceivably 
be born absolutely free from the germs of disease, yet of such 
constitution as to be highly susceptible to them ; and it is easy to 
see how, even within a few days, such a child may become infected 



TUBERCULOSIS PROBABLY NOT INHERITED 357 

from the milk or the lips of a tuberculous mother. This solution 
of the problem is interesting, as allowing place both for the instinc- 
tive experience of the race which seems to show that the disease 
is inherited, while in reality only showing that the disease runs in 
families, such " running " being due, not to the inheritance of the 
disease itself, but to the action of contagion from infected elders 
upon susceptible offspring which have a tendency or predisposition 
to the disease. 



§ 7. — The Probable Truth about Endemic Disease 

One of the common phrases of sanitary science, especially in 
popular discussions, is that which describes disease as " endemic " 
in certain localities. What is meant by the expression is that the 
disease appears to have, in the localities mentioned, a local and 
permanent residence. Expressions of this kind, however, at least 
when applied to infectious disease, have very little value. It was 
formerly said, for example, that typhoid fever was " endemic " in 
Lowell and Lawrence, by which was meant the obvious fact that 
it was always to be found there, with the added implication that 
there was something peculiar in the local conditions, such, for 
example, as a special soil, ground water, or other local condition, 
which made these cities an especially favorable dwelling-place for 
the disease. 

The fact was undoubtedly correct : typhoid fever was always 
or nearly always present; but the implication was incorrect. 
There was nothing in Lowell or Lawrence essentially different 
in respect to soil or people or any other particular (with one 
exception) from the conditions prevailing in Concord, Man- 
chester, Nashua or Haverhill, neighboring cities in the same 
valley. The one exception was the water supply, by which the 
germs of typhoid fever were distributed among the citizens. 
Once this element of infection was removed, the disease nearly 
disappeared, and ceased to be endemic. As a matter of fact, it 
had never been endemic, but was rather constantly epidemic. 

Careful investigation is required, therefore, in any particular 
case before we are justified in concluding that any particular dis- 
ease is endemic, i.e. at home in nature in any particular locality. 



358 APPENDIX 

Such cases do perhaps exist, as, for example, in the case of 
Asiatic cholera in Calcutta, and of malaria in the Roman cam- 
pagna ; but recent advances in the study of the latter disease have 
thrown grave doubt on its necessary endemicity even in the cam- 
pagna, and such cases are nowadays to be regarded as established 
only after the most careful investigation. 

§ 8. — The Belief in Dangers from Atmospheric and 
Telluric Disturbances 

One of the popular beliefs which meets the student of sanitary 
science when he undertakes to discover the sources of epidemic 
disease is an indefinite and occult feeling that there has been 
something mysterious and yet influential in the earth or the air 
sufficient to account for the prevalence of the epidemic in ques- 
tion, if there happens to be one. The author, in the course of his 
studies of typhoid fever, for example, has frequently been told that 
in the opinion of such and such persons the disease prevailing at 
the moment was due to " a late spring," or " a hard winter," or 
to the turning up of the soil in the neighborhood, or to prolonged 
cloudy weather, or some other similar indefinite or obscure cause, 
when perhaps in reality the true cause was an infection of milk 
supply or water supply, or a simple case of secondary infection 
from person to person. 

This form of belief is probably the survival of a very ancient 
and natural tendency in the human race to connect any unusual 
yet well-remembered event with other unusual or especially dis- 
astrous phenomena antecedent to the first in time, and marks 
an interesting reversion to theories commonly accepted in the 
childhood of the race, but long since outgrown. Nothing better 
illustrates the fundamental value of the germ theory of disease 
in placing upon definite material particles the responsibility for 
causation, than the ease with which such primitive theories may 
by its use be discredited. Sanitary science readily allows the direct 
physiological action upon the organism of atmospheric and telluric 
circumstances in exalting or depressing the vital resistance, but 
strenuously denies the direct causation of specific infectious dis- 
eases by such obscure or occult influences. 



DANGER FROM THE HUMAN BREATH 359 

§ 9. — The Belief in Dangers from Damp Cellars 

It has long been accepted as a fact by the more intelligent of 
the human race that damp cellars are unwholesome abodes, but 
the precise reason for this belief, other than the simple results of 
experience, has always been hard to discover. When the germ 
theory of disease became prominent, it was felt by many that the 
solution of this problem was at hand, for what more favorable 
place for the growth of germs than damp, dark cellars, known to 
be inhabited by moulds, and presumably therefore the favorable 
habitat of innumerable other micro-organisms ? 

Investigation, however, has not tended to confirm this theory, for 
the air of cellars, at least of quiet cellars, is practically germ free, 
while upon their walls and floors there is often sufficient dampness 
to keep any germs which may exist there from rising into the air. 
The truth appears to be rather that certain depressing physiologi- 
cal or constitutional effects are produced upon the human organism 
by the conditions which prevail in damp cellars, and that these 
are efficacious in the production of specific disease only by virtue 
of such depression, which lowers the vital resistance and increases 
the susceptibility to specific disease germs derived from any source 
whatsoever. The whole subject, nevertheless, undoubtedly requires 
further elucidation. 

It is interesting to note, in passing, that under the Public 
Health Act of 1875, Section 41, new cellar dwellings were pro- 
hibited, and old ones regulated, in England and Wales. 

§ 10. — The Belief in Dangers from Human Breath 

One of the greatest blessings of the germ theory of disease 
has been the allaying of the fears of mankind in respect to the 
dangers lurking in human breath. Formerly the bedside of an 
infected patient was shunned as a place of extreme danger, largely 
because the breath, which seemed to be the very essence alike of 
the patient's life and of his disease, was believed to be loaded with 
infection, so that all who came within its reach — and that meant, 
of course, within the apartment occupied by the patient — were 
exposed to the gravest dangers. Bacteriology, however, has 
largely done away with this dread, for it has actually demon- 



360 APPENDIX 

strated the amazing fact that the expired breath of the ordinary 
human being is practically germ free. The reason for this appears 
to be that the inspired air is not only drawn in through narrow 
and moist passages, more or less lined with filtering hairs and 
projections which cause the current of air to impinge upon moist 
surfaces, but is also passed through and over porous tissues satu- 
rated with moisture by which any micro-organisms suspended in 
the air are retained. It is still true that a patient in a fit of 
coughing or very hard breathing may throw off particles of sputa 
containing disease germs ; but it is also true that the principal rea- 
son for dreading contact with the human breath, namely, because 
it conveys contagion, is now done away. 

If it be asked what becomes of the micro-organisms thus 
detained within the lungs and on the respiratory passages, the 
answer probably is that they are slowly swept upward by the 
cilia lining the bronchi and trachea, until finally, arriving in 
the mouth, they are either swallowed and pass downward into 
the alimentary canal, or else discharged as expectoration or other- 
wise from the mouth or nose. 



§11. — The Probable Truth about Danger from Putrefac- 
tion and Decay 

Much is heard about the dangers of foods spoiled or partially 
decomposed, especially because these processes are popularly sup- 
posed to give rise readily to the production of poisonous chemical 
bodies roughly classed as "ptomaines." Fortunately, most food 
which is undergoing putrefaction and decay is not appetizing, 
and is, therefore, sedulously avoided. On the other hand, certain 
cheeses, butter, and other food materials are normally partially 
decomposed or "ripened" by bacteria. The truth appears to 
be that in rare cases products may be formed by the presence 
of dangerous bacteria, which are really prejudicial, or even poison- 
ous, to the human organism, but that such bodies are not formed 
or met with nearly as often as popular rumor would lead one to 
suppose. In a certain number of cases the poisoning, if certainly 
present, is due to mineral matters, such as salts of lead, or tin, or 
copper, and not to organic poisons of any kind. 



DANGERS FROiM SPECIAL FOODS AND DRINKS 36 1 

§ 12. — Spoiled Meats 

The dangers from spoiled meat are probably comparatively 
slight, at least broadly speaking, because meat which is so spoiled 
as to be dangerous is generally distasteful. Nevertheless, it is 
possible that canned or preserved meats, or meats which have 
been too much decomposed before cooking, do occasionally give 
rise to serious trouble. 

§ 13. — Ice-cream Poisoning 

Numerous cases are on record in which persons have suffered 
severely after eating ice-cream. In some of these cases mineral 
poisons are to be regarded as the probable source of trouble, hav- 
ing found their way in either with the materials used for flavoring, 
or from uncleanness in the freezers, or from other sources unknown. 
Rarely, it may be that the milk or cream employed has contained 
organisms capable of producing harmful fermentations ; but while 
it is generally assumed that these cases are true cases of ptomaine 
poisoning, much uncertainty exists as to the facts. It is easy for 
a physician, or for any one, called to see patients suffering after 
having eaten ice-cream, or similar foods, to pronounce an opinion 
that the case is one of ptomaine poisoning. The more cautious 
student of sanitary science will, however, require considerable evi- 
dence before finally concluding that such is the case, for he will 
remember that typhoid fever in cities has often been erroneously 
attributed to ice, to water and to various other sources, when in 
reality it was due perhaps to none of the alleged causes, but to some- 
thing totally different and unsuspected, as, for example, milk, and 
in other cases was not even typhoid at all, but perhaps trichinosis. 

§ 14. — Canned Foods 

All that has been said in § 9, 10, n applies, with equal force, to 
canned foods alleged to be the causes of disease. Unquestion- 
ably these, if imperfectly sterilized, may be spoiled and contain 
living micro-organisms. It is quite possible that in certain cases 
nausea or even severe poisoning has been caused by the use of 
such foods, owing to poisonous products of decomposition present 



362 APPENDIX 

in them. As a rule, however, the senses of taste and smell in 
such cases may be depended upon for warning ; and the processes 
employed in canning, and the conditions of unfavorable environ- 
ment which they furnish to disease germs, must be sufficient, in 
the great majority of cases, to cause the destruction of these more 
specific micro-organisms. This subject has already been dwelt 
upon at some length (p. 331). 



INDEX 



Aerobioscope, 113. 

^Etiology, 21. 

Agar-agar, for cultivation of bacteria, 54. 

Age, old, 5, 6. 

Air, microbes of, 113. 

Alcohol, as product of fermentation, 38. 

as toxin, 57. 
Allbutt, T. C, 70. 
Amherst College, typhoid fever from raw 

oysters, 304. 
Animalcules, 47, 48. 
Anopheles, as vehicle of malaria germs, 

95. 96. 
Anthrax, 50. 

Antisepsis, 121, 327, 334. 
Antiseptics, 326, 327. 
Antitoxic serums, 83, 84, 86. 
Antitoxin, 85, 86, 94, 325. 
Arts, the sanitary, 19. 
Asepsis, 121, 311, 312, 326, 334. 
Aseptic surgery, 45. 
Asiatic cholera. See Cholera. 
Atmosphere, the, as a vehicle of disease, 

112. 

AVICENNA, 28. 

Bacillus, 55, 56. 
Bacillus, the typhoid, 168. 
Bacteria, 47, 48, 55. 

disappearance of, in sewage disposal, 
160, 161. 

discovery of, 53. 

in soil, 135. 

thermophilous, 133. 
Bacteriology, establishment of, 53. 

foundation of, 49. 

methods of, 54. 
Baker, Sir George, 78, 79. 
Baker, M. N., 156. 
Bassi, 32. 

Behring, 83, 101, 325. 
Bell, Oswald, 264. 
Board of Health, State, of Mass., 140, 
142. 



Breath, human, not a vehicle of disease, 

359- 
Brieger, 59. 

Budd, Dr. William, 115, 354, 355. 
Burlington, Vt., sewage disposal in, 132. 

water supply of, 234. 
Burdon-Sanderson, 257. 
Burnett, Dr. Waldo Irving, 48. 

Canning, sanitary aspects of, 331. 
Caterham, England, typhoid in, 191, 197. 
Cellars, unfit human abodes, 359. 
Chapin, Dr. C. V., 343. 
Chlorine, normal, 213. 
Cholera, Asiatic, epidemic of, in London 
(1854), 170, 180. 

in Hamburg, Germany, 215. 

in London (1866), 182, 183. 

its germs and their action, 169, 170. 

method of infection in, 97, 98. 

microbe, discovery of, 56. 
Cleanness, the philosophy of, 117. 
Cohn, Ferdinand, 48, 52, 54. 
Cold, antiseptic value of, 328. 
Consumption, not inherited, 356. 
Conn, H. W., 208. 
Contact filters, 159, 163. 
Contagion, 90, 101, 116. 
Cookery, sanitary significance of, 118, 

310. 
Corpuscles, white, of blood, 100. 
Cow-pox, 79, 80. 
Cremation, 341. 
Cultures, liquid, 52-55. 

pure, 52. 

solid, 53. 
Cups, communion, 120. 

drinking, pollution of, 119, 120. 

Death, 5, 8. 

causes of, 8, 9, 10. 
Demonic theory of disease, 22. 
Desiccation, sanitary aspects of, 329. 
Diarrhoea, caused by water supply, 217. 



363 



3^4 



INDEX 



Diarrhceal diseases, conveyed by other 
agencies than drinking water, 
225. 
Dibdin, 159, 163. 
Dimsdale, on inoculation for small-pox, 

80-82. 
Diphtheria, 83, 84, 97, 100. 

microbe, discovery of, 56. 
Dirt, danger from, 117. 

derivation of term, 108, 109, no. 
disposal of, 120, 121. 
Disease, belief in atmospheric causes of, 
358. 
biological significance of, 69. 
definition of, 22. 
causes of, 21-36. 
endemic, 357. 
infectious, its relation to parasitism, 

63-65- 
supposed spontaneous generation of, 

116. 
the principal nominal agent of death, 

9- 

Diseases, contagious, 106. 

constitutional, n. 

diarrhceal, 105. 

environmental, 12, 13. 

eruptive, 105, 113. 

extrinsic, mainly preventable, 13, 14. 

infectious, 90, 104, 113, 117. 

intrinsic, due to defective vital ma- 
chinery, n, 12. 

not caused by odors, 353, 354, 355. 

popular beliefs concerning causes of, 
347. 348, 349- 

zymotic, 117. 
Disinfectants, special, 341, 342. 

vs. antiseptics, 327, 334. 
Disinfection, 121, 123, 334. 

by biological agencies, 339. 

by chemical agencies, 335. 

by mechanical agencies, 338. 

by physical agencies, 336, 337. 

intestinal, 343. 

present state of the art, 343. 
Disposal of the dead, sanitary aspects of, 

339. 340- 
Drainage Commission, Mass., 139-141. 
Drainage, definition of, 124, 125. 
Drains, broken, belief in danger from, 

352. 
Drown, Thomas M., 157, 213, 258. 
Dry-earth system, 123. 
Dust and disease, in. 
Dysentery, from drinking-water, 217. 



Earth, as a vehicle of disease, 109, no, 
in. 

the living, no, 127, 134, 135, 137. 
Earthworms, 109, 135, 136. 
Eberth, 56. 
Eddy, H. P., 156. 
Edwards, Jonathan, 80. 
Effluents, sewage from filters, 161. 
Ehrenberg, 48. 
Electrical purification of water and 

sewage, 157. 
Environment, 67-74, IO °- 

sources of infectious material in, 103. 
Environmental diseases, 12. 
Epithelia, as defences, 91, 92. 

as portals of infection, 93, 94, 97. 
Excrement, 108. 
Excreta, disposal of, 123, 124, 125, 126. 

as vehicles of disease, 105, 106, 107. 
Experiment Station, Lawrence, Mass., 
142. 

Farr, William, 36, 56, 94, 103. 

Favus, 13, 33, 66. 

Fermentation, and disease, 38, 39. 

germ theory of, 36, 37, 40. 

in Asiatic cholera, 98. 
Ferments, how they produce disease, 56. 
Ferment-poison theory of disease, 58. 
Filter, municipal, for sewage, at Brock- 
ton, Mass., 146. 

at Framingham, Mass., 146. 
Filters, contact, 159, 163. 

municipal, for water, 238. 

tests of rapid mechanical, for water, 
240. 
Filter-tanks, experimental, at Lawrence, 

Mass., 144. 
Filth, vehicle rather than source of dis- 
ease, 117. 
Filth diseases, 114, 116. 
Filtration. See also Intermittent Filtration. 

intermittent, 143-149. 

value of, in water-supply, 187. 
Fire, as a disinfectant, 121. 
Flies, as vehicles of disease, 96. 
Food, uncooked, as vehicle of disease, 

118, 293. 
Formaline, as disinfectant, 342. 
Fountains, sanitary, 120. 
Fruits, as vehicles of disease, 308, 309. 
Fuller, George W., 240. 

Gaffky, 56. 
Galen, 27. 



INDEX 



365 



Garbage, 120, 121. 
Germs, 47. 

zymotoxic action of, 60. 
Germ theory, 36, 37, 112. 

objections to, 60, 61. 
Germicides, their efficiency, 342. 
Ground water, 226. 

conservation of purity of, 229. 

pollution and purification of, 226, 227, 
228. 

Hagler, 190, 191. 
Hahnemann, 30. 
Harbors, sewage disposal in, 130. 
Hart, Ernest, 265. 
Hazen, Allen, 156, 218, 240. 
Health, definition of, 4. 

in terms of general biology, 69. 
Hill, Hibbert W., 262. 
Hippocrates, 26, 27. 
Human body, as a mechanism, 3-5, 8, 

67, 69, 70. 
Human breath, as a vehicle of disease, 

359- 
Humors, the four, theory of, 26. 
Hygiene, definitions of, 17, 18, 19. 

functions of, 13, 14, 15, 16. 

personal, 15, 19. 

public, 15, 18. 
Hygiology, definition of, 19. 

Ice, as vehicle of infectious disease, 251, 
258, 262. 
epidemics attributed to, 254, 255, 256. 
its purity investigated, 257, 258. 
Ice supply, and the public health, 262. 
Immunity, 75, 81, 83, 99, 315, 316, 324, 

326. 
Immunization, process of, 83, 84. 
Infection, 90, 91. 

by fruits, vegetables, ice-cream, etc., 

308, 309. 
by tuberculous meats, 297. 
by way of the skin, or by wounds, 92, 

93- 94- 
by way of the throat, alimentary canal, 

etc., 96, 97, 98. 
control of, in decomposition and 

decay, 327. 
danger of, from raw shell-fish, 305, 

306. 
of vegetables and small fruits, 153, 

154- 
of water-supply in London epidemic 
of 1866, 184-186. 



prevention of, by exclusion, 311, 313, 
3H. 

prevention of, by insusceptibility, 315. 

primary sources of, 103, 104, 105, 106. 
Infectious diseases, 67. 
Inheritance, importance of, in sanitary 

science, 8. 
Inland waters, pollution of, 139. 

protection of, 141. 
Inoculation, 76, 78. 

for anthrax, 321. 

for small-pox, j-j, 316, 317. 

of antitoxin for diphtheria, 86. 

objections to, 317. 

of tuberculosis, 277. 
Insects, as vehicles of disease, 94. 
Insusceptibility to disease, produced by 
inoculation, 316. 

by antitoxins, 325. 

by vaccination, 318, 319. 

the goal of sanitary science, 315. 
Interment vs. cremation, 341. 
Intermittent filters, anatomy and physi- 
ology of, 145. 
Intermittent filtration, 136-138. 

English experiments on, 137, 138. 

Massachusetts experiments on, 143. 

not mechanical, but biological, 147, 
148. 

objections to, 148. 

theoretical aspects of, 146, 147. 
Isolation, or local quarantine, 313. 

Jenner, 80, 317, 318, 320. 

Kerner, 58, 59. 

Kinnicutt, Leonard P., 159. 

KlRCHER, 47, 53. 

Koch, Robert, 49-56, 60, 356. 

Lakes, sewage disposal in, 129, 130, 132. 

Latour, Cagniard de, 35. 

Lausen (Switzerland), typhoid fever in, 

187-189. 
Lawrence, Mass., Experiment Station, 143. 
Lawrence and Lowell, Mass., typhoid 

fever in, 211. 
Leeuwenhoek, 47, 48, 53. 
Leidy, Joseph, 257. 
Leucomaines, 59. 
Liebig, 33, 34, 36, 50. 
Life, definition of, 69. 

three principal sanitary conditions of, 

70. 
Lister, Sir Joseph, 45, 54. 



366 



INDEX 



Locke, John, 29. 

London, cholera in Broad Street, 170, 

173-177. 
Broad Street well, description of, 179, 
180. 
Lowell and Lawrence, Mass., typhoid 
fever in, 211, 212, 213. 

Malaria, and mosquitoes, 94, 95, 106. 

not due to bad air, 114. 
Massachusetts, experiments on inter- 
mittent filtration, 143. 
McCollom, Dr. J. H., on antitoxins, 86. 
Metschnikoff, 82, 83. 
Miasms, 103, 104, 112. 
Micro-organisms, 48, 49. 

cause, not consequence of disease, 

50. Si- 
infectious, fate of, in sewage purifica- 
tion, 162. 
Microbes, definition of, 48. 
Milk, as food for microbes and mankind, 
263. 
as a germicide, 100. 
as soil for bacteria, 100. 
as a vehicle of infectious disease, 253, 

254- 

as a cause of infants' diseases, 267. 

condensation of, as a sanitary safe- 
guard, 288, 332. 

diphtheria in, 278. 

fermentation of, 265, 266. 

infected by pus, 284. 

modified, 289. 

normal, definition of, 269. 

normal vs. fermented, 266, 267. 

pasteurization of, 287, 332. 

scarlet fever in, 278. 

sterilization of, 286. 

the pollution of, 267, 268. 

tuberculosis in, 276. 
Milk (dairies), sanitary, 290, 291, 292. 
Milkers, requirements of, in modern 

dairies, 291. 
Milk supplies, 119, 121, 122. 

epidemics of typhoid fever in Mass. 
traced to, 273. 

infection of, by cows, 282, 283. 

infection of, by man, 279. 

in hot countries, 272. 

protection of, from infection, 279, 280, 
281, 285. 

protection of, from pollution, 278, 279, 
285. 

systems of, 268, 269, 270, 271. 



Mills, Hiram Francis, 140, 143, 212. 
Montagu, Lady Mary Wortley, 

76, 316. 
Mosquitoes, as carriers of disease, 94. 
as carriers of malaria, 94, 95, 106. 
Murchison, 114, 115. 
Muscardine, 32, 66. 

Nageli, 48. 
Neisser, 94. 
Nencki, 59. 
Nitrification, in sewage purification, 

137. 
Normal chlorine, 213. 

Odors, offensive, not necessarily inju- 
rious, 353, 354. 

One-Hoss Shay, 6, 7. 

Ord, Dr., 355. 

Organism, definition of, 68. 

Oysters, raw, as vehicles of disease, 297, 
298, 299, 304, 307. 

Ozone, 158. 

Paludism, 114. 
Panum, 59. 

Parasite, definition of, 64, 65, 66. 
Parasitism, its relation to infectious dis- 
ease, 63, 64, 65. 
Particulate theory, 66. 
Pasteur, Louis, 37, 40, 41, 45, 48, 49, 52, 

53, 81, 82, 159, 320, 321. 
Pasteurizing, of foods, sanitary aspects 

of, 332. 
Phagocytes, 83, 84, 100, 101. 
Phagocytosis, a theory of immunity, 83, 

100. 
Pickling, sanitary aspects of, 331. 
Plymouth (Penn.), epidemic of typhoid 

in, 1885, 200-205, 255. 
Poisoning, from foods and drinks, 360, 

361. 
Pollution vs. infection, 213, 214. 
Ponds, sewage disposal in, 129, 130. 
Preserving, sanitary aspects of, 330. 
Preventive medicine, 10. 
Prudden, T. M., ii2, 252, 257. 
Ptomaines, 59, 360, 361. 
Public health, definition of, 18. 
Public supplies as public dangers, 221, 

222. 
Public water supplies, purity in, 221-223, 

242. 
Purification of sewage and of water. See 

Sewage, and Water. 



INDEX 



367 



Putrefaction, probable truth about, 360. 
Pythogenic theory, 114, 115. 

Quarantine, 313, 314. 
QUATREFAGES, 44. 

Radcliffe, J. N., 178, 182, 183. 
Rain water, pollution of, by dust, 224. 
pollution of, by the earth, 225, 226. 
Refrigeration, sanitary aspects of, 328. 
Refuse, disposal of, 120. 
Reservoirs, purification of, by stripping, 

241. 
Resistance, vital, 74, 99. 
Rivers, sewage disposal in, 127, 128, 131. 
Rivers Pollution Commission, 148, 154, 

155, 167. 
Rockwell, Dr. John A., 113. 
Roechling, H. A., 349. 
Rolleston, 352. 
Roux, 101, 325. 

Sands, kinds of, adapted for filtration 

146. 
Sanitary science, definitions of, 15, 19. 
Sanitation, function of, 15. 

requires expert supervision, 250. 
Saprophytes, 65. 
Saprophytism, 64. 
Scarlet fever in milk, 264, 278. 
Schizo?nycetes, 48. 
schoenlein, 33. 
Schwann, 36. 
Sepsin, 59. 
Septicaemia, 93. 

Sea, sewage disposal in the, 130, 131. 
Serum, 84, 85. 

as cure and as prevention, 84. 
Serum therapy, 325. 
Sewage, as vehicle of disease, 123, 126. 

as fertilizer, 150, 151, 152, 153. 

composition and properties of, 125, 
126. 

dangerous elements of, 126. 

definition of, 124. 

disposal of, 1 26-131, 136, 138. 

disposal of, by electricity, 156. 

disposal of, by fermentation or putre- 
faction, 158, 159. 

disposal of, by irrigation, 149-153. 

disposal of, on land, experiments on, 
143. 144- 

disposal of, by septic process, 158. 

farms, 152, 153. 

genesis of, 124, 125. 



importance of sanitary disposal of, 

126, 127, 159-162. 
infection of, by typhoid and cholera 

germs, 168, 170. 
oxidization of, 152. 
purification of, 124, 129, 132, 134, 135, 

137- 

purification of, by chemical precipita- 
tion, 154, 155, 156. 

purification of, by dilution, 160. 

purification of, by electricity, 156, 157, 
158. 

purification of, by irrigation, 150, 151. 

theory of self-purification of, 128. 

valuable ingredients of, 154. 
Sewerage, definition of, 124, 125. 
Sewer-gas, 347, 348, 349. 
Shay, the One-Hoss, 6, 7. 
Silkworm disease, description of, 41-44. 
Simon, Sir John, 182. 
Skin, the, as defence against infection, 
91, 92. 

as portal of infection, 93, 95, 96. 
Small-pox, 38, 39, 76-79. 
Smith, Theobald, 75. 
Smoking, sanitary aspects of, 330. 
Snow, Dr. John, 173, 175, 176, 177. 
Snow, pollution of, and by, 224, 225. 
Soil, 108, 109. 
Spirillum, 56, 169. 
Splenic fever, 50. 

Sporadic cases of typhoid fever, 309. 
Sterilized milk, 287. 
Streams, self-purification of, 128, 231. 
Struggle for existence, sanitary aspects 

of, 62, 63, 72, 74. 
Surface-waters, 226, 230. 

conservation of purity of, 240, 241. 
Survival of the fittest, 73. 
Susceptibility, natural, 74, 324. 

the sanitary meaning of, 74, 99, 100. 
Sydenham, Thomas, 29. 
Sylvius, 28. 

Tcenia, 95. 

Taylor, Dr. L. H., 200. 
Taylor, Dr. Michael, 264. 
Tetanus, 56, 94, 104, no. 
Thackrah, 353. 

Thorne-Thorne, Dr., 191, 194, 195. 
Toxin, 57, 59, 67, 97, 324. 
Trichina, 103, 293. 
Trichinosis, 66, 293, 294, 295. 

epidemics of, 296. 
Tuberculin, 283. 



368 



INDEX 



Tuberculosis, discovery of bacillus of, 55. 

in milk, 276. 
Tucker, G. R., 113. 
Tylor, E. B., 22. 
Typhoid fever, 167. 
bacillus of, 168. 
epidemic of, due to impure water, 187, 

188, 189. 
epidemic of, in Lausen, Switzerland, 

in 1872, 187. 
epidemic of, in Caterham, England, 

191, 192, 193, 194. 
epidemic of, in New Haven, Conn., 

216. 
epidemic of, in Plymouth, Penn., 200, 

201. 
epidemic of, in Red Hill, England, 

193. 194. 
epidemic of, traced to infected oysters, 

298-303. 
epidemics of, traced to skimmed 

milk and creameries, 275. 
in Cambridge, Mass., 274. 
in Chicago, 218. 

in cities on the Merrimac River, 207. 
in Lowell and Lawrence, Mass., 211- 

214. 
in Marlborough, Mass., 275. 
in Newburyport, Mass., 214, 215. 
in Somerville, Mass., 274. 
in Springfield, Mass., 273. 
not a pythogenic fever, 115. 
viability of the bacillus of, 104. 
Typhus fever, 116, 320. 

distinction from typhoid, 167. 

Vaccination, for small-pox, 80, 319. 

for anthrax, by Pasteur, 324. 
Vegetables, as vehicles of disease, 308, 

3°9- 
Vibrio, 56, 169. 
Vibrionia, 48. 
Vital Resistance, 74, 75, 98, 99. 

Water. See also Water Supply. 

as a vehicle of infectious disease, 164, 

165. 
as a vehicle of diarrhceal diseases, 

166. 



Water, natural processes of purification 
of, 233. 
purification of, by freezing, 12, 52, 253, 

254. 
quiet, not running, is self-purifying, 

160, 233. 
self-purification of, 231, 232. 
sewage-polluted, a vehicle, not a 
source, of infectious disease, 214, 
215. 
Waters, natural or pure, 165. 

protection of inland, in Mass., 243, 
244. 
Water-carriage system, 123, 124. 
Watersheds, sanitary protection and in- 
spection of, 246, 247, 248, 249. 
Water supply, atmosphere as source of, 
223. 
epidemic of cholera traced to infected, 

182. 
of Burlington, Vt., 234. 
purification of, by dilution and quies- 
cence, 235. 
purification of, by mechanical proc- 
esses, 239. 
purification of, by slow sand filtration, 

237, 238, 239. 
purification of, by storage, 237. 
Wells, theory of infection by, 350. 
Well waters, belief in dangers from, 349, 

35o. 35i- 

Welply, J. J., 276. 

Wesleyan University, typhoid fever epi- 
demic from raw oysters in, 298- 

303. 

Whitehead, Rev. H., and Broad Street 
pump, 177, 178, 181. 

WiDAL, serum test of typhoid, 169. 

Winslow, C. E. A., 251, 259. 

Worcester, Mass., experiments on chemi- 
cal precipitation, 156. 

Wounds, diseases of, 93, 94. 

Yellow fever, 96. 
York, J., 179. 

Zymotic, origin of word, 35. 

diseases, 34, 35, 36, 62. 
Zymotoxic theory, 56, 58, 59, 60, 222, 223. 



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